1. "Flowers are fertilized by insects."

2. Insects in approaching the nectar brush the pollen from the anthers

with various hairy parts of their bodies, and in their motions convey it

to the stigma.

But Sprengel's seeming victory was doomed to be turned to defeat. The

true "secret" was yet unrevealed in his pages. He had given a poser to

Linnæus (C), yet his own work abounded with similar strange

inconsistencies, which, while being scarcely admitted by himself, or

ingeniously explained, were nevertheless fatal to the full recognition

of his wonderful researches. For seventy years his book lay almost

unnoticed.

"Let us not underrate the value of a fact; it will one day flower in a

truth." The defects in Sprengel's work were, after all, not actual

defects. The error lay simply in his interpretation of his carefully

noted facts. As Hermann Müller has said, "Sprengel's investigations

afford an example of how even work that is rich in acute observation and

happy interpretation may remain inoperative if the idea at its

foundation is defective." What, then, was the flaw in Sprengel's work?

Simply that he had seen but _half_ the "secret" which he claimed to have

"discovered." Starting to prove that insects fertilize the flowers, his

carefully observed facts only served to demonstrate in many cases the

reverse--that _insects could not fertilize_ flowers in the manner he had

declared. He was met at every hand, for instance, by floral problems

such as are shown at E and F, where the pollen and the stigma in the

same flower matured at different periods; and even though he recognized

and admitted that the pollen must in many cases be transferred from one

flower to another, he failed to divine that such was actually the common

vital plan involved. It may readily be imagined that his great work

precipitated an intense and prolonged controversy, and incited emulous

investigation by the botanists of his time. Though a few of the more

advanced of his followers, among them Andrew Knight (1799), Köhlreuter

(1811), Herbert (1837), Gärtner (1844), clearly recognized the principle

and foreshadowed the later theory of cross-fertilization, it was not

until the inspired insight of Darwin, as voiced in his "Origin of

Species," contemplated these strange facts and inconsistencies of

Sprengel that their full significance and actual value were discovered

and demonstrated, and his remarkable book, forgotten for seventy years,

at last appreciated for its true worth. Alas for the irony of fate!

Under Darwin's interpretation the very "defects" which had rendered

Sprengel's work a failure now became the absolute witness of a deeper

truth which Sprengel had failed to discern. One more short step and he

had reached the goal. But this last step was reserved for the later

seer. He took the fatal double problem of Sprengel--as shown at E and F,

to express the consummation pictorially--and by the simple drawing of a

line, as it were, as indicated between G and H, instantly reconciled all

the previous perplexities and inconsistencies, thus demonstrating the

fundamental plan involved in floral construction to be not merely

"_insect_ fertilization," the fatal postulate assumed by Sprengel, but

_cross_-fertilization--a fact which, singularly enough, the latter's

own pages proved without his suspicion.

Thus we see the four successive steps in progressive knowledge, from

Grew in 1682, Linnæus, 1735, Sprengel, 1787, to Darwin, 1857-1858, and

realize with astonishment that it has taken over one hundred and

seventy-five years for humanity to learn this apparently simple lesson,

which for untold centuries has been noised abroad on the murmuring wings

of every bee in the meadow, and demonstrated in almost every flower.

This infinite field now open before him, Darwin began his

investigations, and the whole world knows his triumphs. He has been

followed by a host of disciples, to whom his books have come as an

inspiration and ennobling impulse. Hildebrand, Delpino, Axell, Lubbock,

and, latest and perhaps most conspicuous, Hermann Müller, to whom the

American reader is especially referred. "The Fertilization of Flowers,"

by this most scholarly and indefatigable chronicler, presents the most

complete compendium and bibliography of the literature on the subject

that have yet appeared. Even to the unscientific reader it will prove

full of revelations of this awe-inspiring interassociation and

interdependence of the flower and the insect.

Many years ago the grangers of Australia determined to introduce our

red clover into that country, the plant not being native there. They

imported American seed, and sowed it, with the result of a crop

luxuriant in foliage and bloom, but not a seed for future sowing! Why?

Because the American bumblebee had not been consulted in the

transaction. The clover and the bee are inseparable counterparts, and

the plant refuses to become reconciled to the separation. Upon the

introduction and naturalization of the American bumblebee, however, the

transported clover became reconciled to its new habitat, and now

flourishes in fruition as well as bloom.

Botany and entomology must henceforth go hand-in-hand. The flower must

be considered as an embodied welcome to an insect affinity, and all

sorts of courtesies prevail among them in the reception of their invited

guests. The banquet awaits, but various singular ceremonies are enjoined

between the cup and the lip, the stamens doing the hospitalities in

time-honored forms of etiquette. Flora exacts no arbitrary customs. Each

flower is a law unto itself. And how expressive, novel, and eccentric

are these social customs! The garden salvia, for instance, slaps the

burly bumblebee upon the back and marks him for her own as he is ushered

in to the feast. The mountain-laurel welcomes the twilight moth with an

impulsive multiple embrace. The desmodium and genesta celebrate their

hospitality with a joke, as it were, letting their threshold fall

beneath the feet of the caller, and startling him with an explosion and

a cloud of yellow powder, suggesting the day pyrotechnics of the

Chinese. The prickly-pear cactus encloses its buzzing visitor in a

golden bower, from which he must emerge at the roof as dusty as a

miller. The barberry, in similar vein, lays mischievous hold of the

tongue of its sipping bee, and I fancy, in his early acquaintance,

before he has learned its ways, gives him more of a welcome than he had

bargained for. The evening primrose, with outstretched filaments,

hangs a golden necklace about the welcome murmuring noctuid, while the

various orchids excel in the ingenuity of their salutations. Here is one

which presents a pair of tiny clubs to the sphinx-moth at its threshold,

gluing them to its bulging eyes. Another attaches similar tokens to the

tongues of butterflies, while the cypripedium speeds its parting guest

with a sticking-plaster smeared all over its back. And so we might

continue almost indefinitely. From the stand-point of frivolous human

etiquette we smile, perhaps, at customs apparently so whimsical and

unusual, forgetting that such a smile may partake somewhat of

irreverence. For what are they all but the divinely imposed conditions

of interassociation? say, rather, interdependence, between the flower

and the insect, which is its ordained companion, its faithful messenger,

often its sole sponsor--the meadows murmuring with an intricate and

eloquent system of intercommunings beside which the most inextricable

tangle of metropolitan electrical currents is not a circumstance. What a

storied fabric were this murmurous tangle woven day by day, could each

one of these insect messengers, like the spider, leave its visible trail

behind it!

As a rule, these blossom ceremonies are of the briefest description.

Occasionally, however, as in the cypripedium and in certain of the

arums, or "jack-in-the-pulpit," and aristolochias, the welcome becomes

somewhat aggressive, the guest being forcibly detained awhile after tea,

or, as in the case of our milkweed, occasionally entrapped for life.

[Illustration]

From this companionable point of view let us now look again at the

strange curved stamen of the sage. Why this peculiar formation of the

long curved arm pivoted on its stalk? Considered in the abstract, it can

have no possible meaning; but taken in association with the insect to

which it is shaped, how perfect is its adaptation, how instantly

intelligible it becomes! Every one is familiar with the sage of the

country garden, its lavender flowers arranged in whorls in a long

cluster at the tips of the stems. One of these flowers, a young one from

the top of the cluster, is shown at A (Fig. 4), in section, the long

thread-like pistil starting from the ovary, and curving upward beneath

the arch of the flower, with its forked stigma barely protruding (B).

There are two of the queer stamens, one on each side of the opening of

the blossom, and situated as shown, their anthers concealed in the hood

above, and only their lower extremity appears below, the minute growth

near it being one of the rudiments of two former stamens which have

become aborted. If we take a flower from the lower portion of the

cluster (D), we find that the thread-like pistil has been elongated

nearly a third of an inch, its forked stigma now hanging directly at the

threshold of the flower. The object of this will be clearly demonstrated

if we closely observe this bee upon the blossoms. He has now reached the

top of the cluster among the younger blossoms. He creeps up the

outstretched platform of the flower, and has barely thrust his head

within its tube when down comes the pair of clappers on his back (C).

Presently he backs out, bearing a generous dab of yellow pollen, which

is further increased from each subsequent flower. He has now finished

this cluster, and flies to the next, alighting as usual on the lowermost

tier of bloom. In them the elongated stigma now hangs directly in his

path, and comes in contact with the pollen on his back as the insect

sips the nectar. Cross-fertilization is thus insured; and, moreover,

cross-fertilization not only from a distinct flower, but from a separate

cluster, or even a separate plant. For in these older stigmatic flowers

the anther as it comes down upon his back is seen to be withered, having

shed its pollen several days since, the supply of pollen on the bee's

body being sufficient to fertilize all the stigmas in the cluster, until

a new supply is obtained from the pollen-bearing blossoms above. And

thus he continues his rounds.

[Illustration: Fig. 4]

The sage is a representative of the large botanical order known as the

Mint family, the labiates, or gaping two-lipped flowers, the arched hood

here answering to the upper lip, the spreading base forming the lower

lip, which is usually designed as a convenient threshold for the insects

while sipping the nectar deep within the tube. This mechanism of the

sage is but one of many curious and various contrivances in the Mint

family, all designed for the same end, the intercrossing of the flowers.

While each family of plants is apt to favor some particular general

plan, the modifications in the various species seem almost without

limit.

Let us now look at the Heath family. The family of the heath, cranberry,

pyrola, Andromeda, and mountain-laurel--how do these blossoms welcome

their insect friends? This group is particularly distinguished by the

unusual exception in the form of its anthers, which open by pores at

their tips, instead of the ordinary side fissures. Two or three forms of

these anthers are shown in my row of stamens (Fig. 1).

Seen thus in their detached condition, how incomprehensible and

grotesque do they appear! And yet, when viewed at home, in their

bell-shaped corollas, their hospitable expression and greeting are seen

to be quite as expressive and rational as those of the sage. Take the

mountain-laurel, for instance; what a singular exhibition is this which

we may observe on any twilight evening in the laurel copse, the dense

clusters of pink-white bloom waited upon by soft-winged fluttering

moths, and ever and anon celebrating its cordial spirit by a mimic

display of pyrotechnics as the anthers hurl aloft their tiny showers of

pollen!

Every one is familiar with the curious construction of this flower, with

its ten radiating stamens, each with its anther snugly tucked away in a

pouch at the rim of its saucer-shaped corolla. Thus they appear in the

freshly opened flower, and thus will they remain and wither if the

flower is brought indoors and placed in a vase upon our mantel. Why?

Because the hope of the blossom's life is not fulfilled in these

artificial conditions; its natural counterpart, the insect, has failed

to respond to its summons.

[Illustration]

But the twilight cluster in the woods may tell us a pretty story.

Here a tiny moth hovers above the tempting chalice, and now settles upon

it with eager tongue extended for the nectar at its centre. What an

immediate and expressive welcome! No sooner has this little feathery

body touched the filaments than the eager anthers are released from

their pockets, and, springing inwards, clasp their little visitor, at

the same time decorating him with their compliments of webby pollen (A,

Fig. 5).

The nectary now drained of its sweets, the moth creeps or flutters to a

second blossom, and its pollen-dusted body thus coming in contact with

its stigma, cross-fertilization is accomplished. The pollen of the

laurel differs from that of most of the Heath blooms, its grains being

more or less adherent by a cobwebby connective which permeates the mass

as indicated in my magnified representation (B, Fig. 5).

[Illustration: Fig. 5]

It is probable that an accessory cross-fertilization frequently results

from a mass of the pollen falling directly upon the stigma of a

neighboring blossom, or even upon its own stigma, but even in the

latter case, as has been absolutely demonstrated as a general law by the

experiments of Darwin, the pollen from a separate flower is almost

invariably prepotent, and leads to the most perfect fruition, and thus

to the survival of the fittest--the cross-fertilized. And, in any event,

the insect is to be credited for the release of the tiny catapults by

which the pollen is discharged. But the laurel may be considered as an

exceptional example of the Heath family. Let us look at a more perfect

type of the order to which it belongs, the globular blossom of the

Andromeda (_A. ligustrina_).

[Illustration]

Only a short walk from my studio door in the country I recently observed

its singular reception to the tiny black-and-white banded bee, which

seems to be its especial companion, none the less constant and forgiving

in spite of a hospitality which, from the human stand-point, would

certainly seem rather discouraging. Fancy a morning call upon your

particular friend. You knock at the door, and are immediately greeted at

the threshold with a quart of sulphur thrown into your face. Yet this is

precisely the experience of this patient little insect, which manifests

no disposition to retaliate with the concealed weapon which on much less

provocation he is quick to employ. Here he comes, eager for the fray.

He alights upon one of the tiny bells scarce half the size of his body.

Creeping down beneath it, he inserts his tongue into the narrowed

opening. Instantly a copious shower of dust is poured down upon his face

and body. But he has been used to it all his life, and by heredity he

knows that this is Andromeda's peculiar whim, and is content to humor it

for the sweet recompense which she bestows. The nectar drained, the

insect, as dusty as a miller, visits another flower, but before he

enters must of necessity first pay his toll of pollen to the drooping

stigma which barely protrudes beneath the blossom's throat, and the

expectant seed-pod above welcomes the good tidings with visions of

fruition.

[Illustration: Fig. 6]

And how beautiful is the minute mechanical adaptation by which this end

is accomplished! This species of Andromeda is a shrub of about four feet

in height, its blossoms being borne in close panicled clusters at the

summit of the branches. The individual flower is hardly more than an

eighth of an inch in diameter. From one of three blossoms I made the

accompanying series of three sectional drawings (Fig. 6). The first

shows the remarkable interior arrangement of the ten stamens surrounding

the pistil. The second presents a sectional view of these stamens,

showing their peculiar S-shaped filaments and ring of anthers--one of

the latter being shown separate at the right, with its two pores and

exposed pollen. The freshly opened blossom discloses the entire ring of

anthers in perfect equilibrium, each with its two orifices closed by

close contact with the style, thus retaining the pollen. It will readily

be seen that an insect's tongue, as indicated by the needle, in probing

between them in search for nectar, must needs dislocate one or more of

the anthers, and thus release their dusty contents, while the position

of the stigma below is such as to escape all contact.

[Illustration]

In most flowers, with the exception of the orchids, the stamens and

pollen are plainly visible; but who ever sees the anthers of the

blue-flag? Surely none but the analytical botanist and the companion

insect to whom it is so artfully adjusted and so demonstrative. This

insect is likely to be either a bumblebee or a species of large fly. In

apt illustration of Sprengel's theory of the "path-finder" or

honey-guide, the insect does not alight at the centre of the flower, but

upon one of the three large drooping sepals, whose veins, converging to

the narrow trough above, indicate the path to the nectar. Closely

overarching this portion is a long and narrow curved roof--one of three

divisions to the style, each surmounting its veined sepals. Beneath this

our visiting bee disappears, and a glance at my sectional drawing shows

what happens. Concealed within, against the ridge-pole, as it were, the

anther awaits his coming, and in his passage to and from the nectar

below spreads its pollen over his head and back. Having backed out of

this segment of the blossom (A, Fig. 7), he proceeds to the next; but

the shelf-like stigma awaits him at the door, and scrapes off or rubs

off a few grains of the pollen from his back (B). Thus he continues

until the third segment is reached, from which he carries away a fresh

load of pollen to another flower. It will be seen that only the outer

side of this appendage is stigmatic, and that it is thus naturally

impossible for the blue-flag to self-fertilize--only one instance of

thousands in which the anther and stigma, though placed in the closest

proximity, and apparently even in contact--seemingly with the _design_

of self-fertilization--are actually more perfectly separated

functionally than if in separate flowers, the insect alone consummating

their affinity.

[Illustration: Fig. 7]

[Illustration]

In some flowers this separation is effected, as I have shown, by their

maturing at different periods; in others, as in the iris, by mere

mechanical means; while in a long list of plants, as in the willow,

poplar, hemp, oak, and nettle, the cross-fertilization is absolutely

necessitated by the fact of the staminate and stigmatic flowers being

either separated on the same stalk or on different plants, the pollen

being carried by insects or the wind. We may see a pretty illustration

of this in the little wild flower known as the devil's-bit (_Chamælirium

luteum,_), whose long, white, tapering spire of feathery bloom may often

be seen rising above the sedges in the swamp. Two years ago I chanced

upon a little colony of four or five plants at the edge of a bog. The

flowers, all of them, were mere petals and stamens (B, Fig. 8). I looked

in vain for a single stigmatic plant or flower; but far across the

swamp, a thousand feet distant, I at length discovered a single spire,

composed entirely of pistillate flowers, as shown in A (Fig. 8), and my

magnifying-glass clearly revealed the pollen upon their

stigmas--doubtless a welcome message brought from the isolated affinity

afar by some winged sponsor, to whom the peculiar fragrance of the

flower offers a special attraction, and thus to whom the fortunes of the

devil's-bit have been committed.

[Illustration]

[Illustration: Fig. 8]

The presence of fragrance and honey in a dioecious flower may be

accepted in the abstract as almost conclusive of an insect affinity, as

in most flowers of this class, notably the beech, pine, dock, grasses,

etc., the wind is the fertilizing agent, and there is absence alike of

conspicuous color, fragrance, and nectar--attributes which refer alone

to insects, or possibly humming-birds in certain species.

Look where we will among the blossoms, we find the same beautiful plan

of intercommunion and reciprocity everywhere demonstrated. The means

appear without limit in their evolved--rather, I should say,

involved--ingenuity. Pluck the first flower that you meet in your stroll

to-morrow, and it will tell you a new story.

[Illustration]

Only a few days since, while out on a drive, I passed a luxuriant clump

of the plant known as "horse-balm." I had known it all my life, and

twenty years previously had made a careful analytical drawing of the

mere botanical specimen. What could it say to me now in my more

questioning mood? Its queer little yellow-fringed flowers hung in

profusion from their spreading terminal racemes. I recalled their

singular shape, and the two outstretched stamens protruding from their

gaping corolla, and could distinctly see them as I sat in the carriage.

I had never chanced to read of this flower in the literature of

cross-fertilization, and murmuring, half aloud, "What pretty mystery is

yours, my Collinsonia?" prepared to investigate.

[Illustration: Fig. 9]

What I observed is pictured severally at Fig. 9, the flowers being

shown from above, showing the two spreading stamens and the decidedly

exceptional unsymmetrical position of the long style extending to the

side. A small nectar-seeking bumblebee had approached, and in alighting

upon the fringed platform grasped the filaments for support, and thus

clapped the pollen against his sides. Reasoning from analogy, it would

of course be absolutely clear that this pollen has thus been deposited

where it will come in contact with the stigma of another flower. So, of

course, it proved. In the bee's continual visits to the several flowers

he came at length to the younger blooms, where the forked stigmas were

turned directly to the front, while the immature stamens were still

curled up in the flower tubes. Even the unopened buds showed a number of

species where the early matured stigma actually protruded through a

tiny orifice in precisely the right position to strike the pollen-dusted

body of the bee, as he forced his tongue through the tiny aperture.[A]

[Footnote A: In numerous instances observed since the above was written

I have noted the larger bumblebees upon the blossom. These insects have

a different method of approach, hanging beneath the flower, the anthers

being clapped against their thorax at the juncture of the wings, instead

of the abdomen, as in the smaller bee.]

[Illustration]

If their dainty mechanism excite our wonder, what shall be said of the

revelations in the great order of the Compositæ, where each so-called

flower, as in the dandelion, daisy, cone-flower, marigold, is really a

dense cluster of minute flowers, each as perfect in its construction as

in the examples already mentioned, each with its own peculiar plan

designed to insure the transfer of its own pollen to the stigma of its

neighbor, while excluding it from its own?

All summer long the cone-flower, Fig. 10 (_Rudbeckia hirta_), blooms in

our fields, but how few of us imagine the strange processes which are

being enacted in that purple cone! Let us examine it closely. If we

pluck one of the blossom's heads and keep it in a vase over-night, we

shall probably see on the following morning a tiny yellow ring of pollen

encircling the outer edge of the cone. In this way only are we likely

to see the ring in its perfection, as in a state of nature the wind and

insects rarely permit it to remain.

[Illustration: Fig. 10]

If we now with a sharp knife make a vertical section, as shown at A

(Fig. 3), we may observe the conical receptacle studded with its embryo

seeds, each bearing a tiny tubular blossom. Three distinct forms of

these flowers are to be seen. The lower and older ones are conspicuous

by their double feathery tails, the next by their extended anthers

bearing the pollen at their extremity, and above these again the buds in

all stages of growth. These various states are indicated in Fig. 11.

As in all the Compositæ, the anthers are here united in a tube, the

pollen being discharged within. At the base of this anther-tube rises

the pistil, which gradually elongates, and like a piston forces out the

pollen at the top. Small insects in creeping over the cone quickly

dislodge it. In the next stage the anthers have withered, the

flower-tube elongated, and the top of the two-parted pistil begins to

protrude, and at length expands its tips, disclosing at the centre the

stigmatic surface, which has until now been protected by close contact.

(See section.)

[Illustration: Fig. 11]

A glance at Fig. 11 will reveal the plan involved. The ring of pollen is

inevitably scattered to the stigmas of the neighboring flowers, and

cross-fertilization continually insured. Similar contrivances are to be

found in most of the Compositæ, through the same method being variously

applied.

Perhaps even more remarkable than any of the foregoing, which are more

or less automatic in their movements, is the truly astonishing and

seemingly conscious mechanism displayed in the wild arum of Great

Britain--the "lords and ladies" of the village lanes, the foreign

counterpart of our well-known jack-in-the-pulpit, or Indian-turnip, with

its purple-streaked canopy, and sleek "preacher" standing erect beneath

it. A representation of this arum is shown in Fig. 12, and a cross

section at A, properly indexed.

[Illustration: Fig. 12]

How confidently would the superficial--nay, even careful--examination of

one of the old-time botanists have interpreted its structure: "How

simple and perfect the structure! Observe how the anthers are placed so

that pollen shall naturally fall directly on the stigmas and fertilize

them!" Such would indeed appear to be intended, until it is actually

discovered that the _stigmas have withered_ when the pollen is shed--a

device which, acting in association with the little ring of hairs, tells

a strange story. It is not my fortune to have seen one of these singular

blossoms, but from the description of the process of fertilization given

in Hermann Müller's wonderful work, aided by a botanical illustration

of the structure of the flower, I am readily enabled to picture the

progressive stages of the mechanism.

[Illustration: Fig. 13]

In the first stage (B, Fig. 13) small flies with bodies dusted with

pollen from a previous arum blossom (for insects, as a rule, remain

faithful or partial to one species of flowers while it is in bloom) are

entering the narrowed tube, easily passing through the drooping fringe

of hairs. Nectar is secreted by the stigmas, and here the flies

assemble, thus dusting them with pollen. Their appetite temporarily

satisfied, the insects seek escape, but find their exit effectually

barred by the intruding fringe of hairs (C). In this second stage the

stigmas, having now been fertilized, have withered, at the same time

exuding a fresh supply of nectar, which again attracts the flies,

whereupon, as shown at D, the anthers open and discharge their pollen

upon the insects. In the fourth stage (E), all the functions of the

flower having now been fulfilled, the fringe of hairs withers, and the

imprisoned pollen-laden flies are permitted to escape to another flower,

where the beautiful scheme is again enacted.

In a paper of this kind it is of course possible only to hint at a few

representative examples of floral mechanisms, but these would be indeed

incomplete without a closing reference to that wonderful tribe of

flowers with which the theory of cross-fertilization will ever be

memorably associated. I have previously alluded to the absolute

dependence of the red clover upon the bumblebee. This instance may be

considered somewhat exceptional, though numerous parallel cases are

known. Among ordinary flowers this intervention of the insect is largely

a _preferable_ intention, and though almost invariably fulfilled, a

large proportion of flowers still retain, as a _dernier ressort_, the

power of at least partial self-fertilization and perpetuity in the

absence or neglect of their insect counterpart.

[Illustration: Fig. 14]

The numerous and conclusive demonstrations of Darwin, however, have

proved that in the competition for existence such self-fertilized

offspring quickly yield before the progeny of cross-fertilization.

But the distinctive feature of the orchids lies in the fact that this

dependence on the insect is wellnigh universally absolute. Here are a

great host of plants which are doomed to extinction if for any reason

their insect sponsors should permanently neglect them. The principal

botanical feature which differentiates the orchid from other plants lies

in the construction of the floral organs, the pistil, stigma, and

anthers here being united into a distinct part known as the column. The

pollen is, moreover, peculiar, being collected into more or less compact

masses, and variously concealed in the flower. Some of these are

club-shaped, with a viscid extremity, others of the consistency of a

sticking-plaster, and all are hidden from external view in pouches and

pockets, from which they never emerge unless withdrawn on the body of an

insect. The various devices by which this removal is insured are most

astonishing and awe-inspiring. Nor is it necessary to go to the

conservatory for a tropical specimen, as is commonly supposed. An orchid

is an orchid wherever it grows, and our native list of some fifty

species will afford examples of as strange mechanical adaptations as are

to be found among Darwin's pages. Indeed, a few of our American species

are there described. One example will suffice for present

illustration--the sweet-pogonia or grass-pink of our sedgy swamps

(_Pogonia ophioglossoides_). Its solitary rosy blossom, nodding on its

slender stem above the sedges, is always a welcome episode to the

sauntering botanist, and its perfume, suggesting ripe red raspberries,

is unique in the wild bouquet. One of these flowers is shown in profile

at Fig. 14, its various parts indexed. Concealed behind the petals is

the column, elsewhere indicated from various points of view. Attracted

by its color and fragrance, the insect seeks the flower; its

outstretched fringy lip offers a cordial invitation at its threshold,

and conducts its visitor directly to the sweets above. In his entrance,

as seen at D (Fig. 15), the narrowed passage compresses his back against

the underside of the column, forcing his head and back against the

stigma. The effect of this inward pressure, as will be seen, only serves

to force the anther more firmly within its pocket; but as the insect,

having drained the nectar, now backs out, note the result. The lip of

the anther catches upon the back, swings outward on its hinge, and

deposits its sticky pollen all over the insect's back, returning to its

original position after his departure. In another moment he is seen upon

another blossom, as at D again, his pollen-laden back now coming in

contact with the stigma, and the intention of the blossom is

accomplished; for without this assistance from the insect the little

lid remains close within its pocket, and the pollen is thus retained.

[Illustration: Fig. 15]

What startling disclosures are revealed to the inward eye within the

hearts of all these strange orchidaceous flowers! Blossoms whose

functions, through long eras of adaptation, have gradually shaped

themselves to the forms of certain chosen insect sponsors; blossoms

whose chalices are literally fashioned to bees or butterflies; blossoms

whose slender, prolonged nectaries invite and reward the murmuring

sphinx-moth alone, the floral throat closely embracing his head while it

attaches its pollen masses to the bulging eyes, or perchance to the

capillary tongue! And thus in endless modifications, evidences all of

the same deep vital purpose.

Let us then content ourselves no longer with being mere

"botanists"--historians of structural facts. The flowers are not mere

comely or curious vegetable creations, with colors, odors, petals,

stamens, and innumerable technical attributes. The wonted insight alike

of scientist, philosopher, theologian, and dreamer is now repudiated in

the new revelation. Beauty is not "its own excuse for being," nor was

fragrance ever "wasted on the desert air." The seer has at last heard

and interpreted the voice in the wilderness. The flower is no longer a

simple passive victim in the busy bee's sweet pillage, but rather a

conscious being, with hopes, aspirations, and companionships. The insect

is its counterpart. Its fragrance is but a perfumed whisper of welcome,

its color is as the wooing blush and rosy lip, its portals are decked

for his coming, and its sweet hospitalities humored to his tarrying; and

as it finally speeds its parting affinity rests content that its life's

consummation has been fulfilled.

_A HONEY-DEW PICNIC_

[Illustration]

Several of our notable as well as notorious human, social, and civic

customs find their prehistoric prototypes in the insect kingdom. The

monarchical institution sees its singular prophecy in the domestic

economy of the bees. War and slavery have always been carried on

systematically and effectually by ants, and, according to Huber and

other authorities, agriculture, gardening, and an industry very like

dairy farming have been time-honored customs among this same wise and

thrifty insect tribe, whose claims to thoughtful consideration were so

long ago voiced by Solomon of proverbial fame. Thévenot mentions

"Solomon's ant" as among the "beasts which shall enter paradise."

Indeed, the human saint as well as sluggard may "go to the ant" for many

suggestive hints and commentaries.

These are only a few of the more notable parallelisms which suggest

themselves. But others are not wanting if we care to follow the subject.

In addition to the many models of thrift and virtuous industry,

embodying types of many of the trade employments known to humanity, have

we not also among these "meadow tribes" our luxurious "idlers" and

"exquisites," the butterflies and flower-haunting flies and "dandy"

beetles; and, opposed to all these, the suggestive antithesis of the

promiscuous marauders, thieves, and brigands everywhere interspersed?

Thus we have our individual insect assassin and assassination organized

in war; so, on the other hand, have we our insect merrymakers; why not,

then, our picnic or carnival?

Such I am moved to call the singular episode which I observed last

summer, and which I have endeavored to picture as true to the life as

possible in the accompanying presentment The sceptic will perhaps

remark on examination that the scene is characterized by somewhat too

free a license to warrant the ideal of a "picnic." But he is

hypercritical. There are picnics and picnics--picnics of high and of low

degree. Do I not recall more than one notorious festive outing of the

"next lower than the angels" in which the _personnel_ seemed about

similarly proportioned, and the fun and attraction comparatively related

to the license?

One July afternoon a year ago I was returning home from one of my

botanizing strolls. I had just emerged from a deep wood, and was

skirting its border, when my attention was caught by a small fluttering

swarm of butterflies, which started up at my approach and hovered about

a blossoming blackberry bush a few yards in advance of me at the side of

my path. The diversity of the butterfly species in the swarm struck me

as singular, and the mere allurement of the blackberry blossoms--not

usually of especial attraction to butterflies--could hardly explain so

extensive a gathering. Here was the great yellow swallow-tail

(_Turnus_), red admiral (_Atlanta_), small yellow butterfly

(_Philodice_), white cabbage-butterfly, comma and semicolon, and

numerous small fry, fluttering about me in evident protest against my

intrusion. They showed no inclination to vacate the premises, so, in

pursuance of one of the first articles of my saunterer's creed, I

concluded to retreat softly a few paces and watch for developments. One

by one the swarm sought their original haunt, settling on the bramble,

and I now noticed that only in occasional instances did the insects seek

the flowers, the attraction seeming to be confined to the leaves. I

stole up softly for a nearer point of observation, and could now

distinctly see the beautiful yellow and black open wings of the

swallow-tail softly gliding or gently fluttering as it hung from the

edge of a leaf, while it explored its surface with its uncoiled

capillary tongue. Just beyond my _Turnus_, on another leaf, I now noted

a new presence, the orange Aphrodite butterfly, silvery spotted, its

nether wings being folded over its back, too much absorbed to have been

startled by my first approach. Occasionally, without any cause which I

could detect from my present position--certainly in no way connected

with my presence--a small swarm of the butterflies would rise in a

flutter above the bush, as though actuated by a common whim--a brief

winged tangle in which a beautiful sprite of velvety black hovering in a

globular halo, shot through with two white semicircular arcs, was always

a momentary feature.

Carefully stealing through the tall grass, I now approached to within

touching distance of the haunt, and was soon lost in mingled wonder,

amusement, and surprise at the picnic now disclosed, the occasional

butterfly swarm being now easily explained. From my first point of view

only the top of the bramble spray was visible above the grass, and by

far the most interesting portion of the exercises had been concealed

from view. The butterflies, while naturally the most conspicuous

element, were now seen to be in a small minority among the insect

gathering, the bramble leaves being peopled with a most motley and

democratic assemblage of insects. Class distinctions were apparently

forgotten in the common enthusiasm; the plebeian bluebottle and blowfly

now consorted with Aphrodite and sipped at the same drop. Many a leaf

was begemmed with the blue bodies closely set side by side or in a close

cluster. The meat-fly, house-fly, and horse-fly made themselves

promiscuous in every portion of the spray, and what with the

rainbow-eyed and ruby-eyed flies, black and silver-banded flower-flies,

and other tiny, restless, iridescent atoms of the fly fraternity, the

family of _Musca_ was well represented at the feast.

Nor were these all the guests at the banquet--for banquet there

certainly was, judging from the eager sipping and crowding everywhere

upon the leaves, the flowers even yet, as I first noticed, seeming to

have little attraction.

I have no direct means of knowing as to the social discrimination of the

host as shown in the entertainment, for that invitations were issued the

subsequent facts would show. But I have good reasons for believing, from

the course of events, that the gathering included a number of

questionable personages that were not counted upon.

Here, for instance, was an overwhelming contingent of the whole tough

gang of wasps and hornets--brown wasps from under the eaves and fences;

black hornets from the big paper nests; yellow-jackets from where you

please; deep steel-blue wire-waisted wasps from the mud cells in the

garret, to say nothing of an occasional longer-waisted digger-wasp, and

a host of their allied lesser associates scattered around generously

among the assemblage.

Every now and then a big darning-needle took a shimmering circuit about

the bush, and doubtless knew what he was about; as did also what at

first glimpse appeared to be a big bumblebee, which seemed to find

attraction in the neighborhood, although he seldom alighted upon the

leaves, preferring to sit upon a neighboring weed and watch his

opportunities.

I have thus described a few of the more prominent guests or personages

present at the feast. But I have reported little of their "goings on."

Doubtless there were appropriate toasts and responses, or what in bug

etiquette answered to this seemingly indispensable human fad, while as

to that other festive social essential of after-dinner speeches, coupled

in this case with most vigorous discussion, I am certain the air was

blue with something of this sort, if the eloquent pantomime bore any

significance. Here, for instance, is one isolated, but frequent,

episode. A peaceable little group of plain bluebottle-flies, with but a

single thought, are all sipping at the same drop in contentment. A brief

respite, for now the tips of a pair of inquisitive antennæ appear from

the under edge of the leaf upon which they are sipping, and gingerly

explore the upper surface. They are quickly followed by the covetous

almond-eyed gaze of a brown wasp, that now steals cautiously around to

the upper surface, and appears wholly engrossed in licking the leaf.

Nearer and nearer he sidles up to the group of flies, and now with

deliberate purpose and open jaws makes a dash among them. But they are

too quick for him, and are away in a glittering blue tangle, which

finally concentrates itself upon a neighboring leaf, where the eager

tippling is immediately resumed. The wasp now holds the fort, and seems

in no mood to be trifled with. With head and fore feet upraised and open

jaws he seems "spoiling for a fight," and ready to make war upon the

first comer. But no, he is evidently expecting a friend that, I now

observe, approaches him determinedly down the stem of the leaf. The

new-comer, a brown wasp like himself, is now at close range, and in an

instant more, without any visible courteous preliminaries, the two set

upon each other with a common enthusiasm, and with jaws working and

stings fencing the interlocked combatants fall to the ground for a

finish. I presume the affair was carried to the fourteenth round without

any undue interference.

Another and another of these friendly meetings between them and other

wasps took place in the half-hour in which I watched the sport. There

were lulls in hostilities, during which an atmosphere of perfect peace

and harmony seemed to reign around my bramble-bush. The flies were

motionless in their ecstasy, and the hornet element seemed by common

consent to keep temporarily shady, and even the butterflies seemed to

forget that they had wings. But not for long, for now with a shimmering

glitter our darning-needle invades the scene, and retires to a

convenient perch with a ruby-eyed fly in his teeth, while a swarm of

very startled butterflies tells conspicuously of the demoralization

which he has left in his path. Among the butterfly representatives I at

length observed one individual which at first had escaped me, an

exclusive white cabbage-butterfly which sipped quietly at his leaf in

the shade, and seemed to take little interest in the disreputable

actions of his associates. Nothing could move him or entice him away

from his convivial employment. But, alas! his folly soon found him out,

for, on happening to look again, I observed he had found a new

acquaintance--a hornet that had evidently been long desirous of meeting

him. One by one I saw my butterfly's dismembered wings fall to the

grassy jungle below, while a big black wasp proceeded to enjoy the

collected sweets which he had doubtless observed were being so carefully

stored away there in the shady retreat.

[Illustration]

And now my pretty black butterfly--no, it proved to be the little

day-flying grape-vine-moth, the eight-spotted black _Alypia_--appeared

from some unseen source, and spun his crapy white-streaked halo among

the leaves, at length settling among a little company of flies. Softly

behind him creeps a brown wasp (_Polistes_), with his mouth watering,

while from the opposite quarter a steel-blue mud-wasp approaches, with

apparently similar designs. Neither invader sees the other.

Simultaneously, as though answering to a signal, the two make a dash at

the moth; but he is too quick for them. In a twinkling he is off in his

pretty halo again, while the two disappointed contestants have clinched,

and with stings and jaws vigorously plying fall to the jungle below, and

seek satisfaction in mortal combat.

Here is a pretty little yellow and black banded flower-fly, which is

having a quiet little picnic all by himself on a bed of yarrow bloom

close by. But a big black paper-hornet has suddenly seen an attraction

hither also, and is soon creeping stealthily among the blossoms with a

wild and hungry look. But the hornets seemed to waste their time on the

flies. Seemingly confident in their less complicated wing machinery, the

two-winged fly rarely sought escape until within very close range of his

enemy, and his resources never seemed to disappoint him at the critical

moment.

Among the insect assemblage was a large number of ants of all kinds and

sizes, the common large black species being conspicuous. Here is one

creeping and sipping along a grass stem. A small digger-wasp likes this

grass stem too, but instead of exchanging courtesies on the subject, the

wasp proceeds to bite the ant's head off without ceremony, and continues

sipping at the stem as though decapitation were a mere casual incident

in its daily walk.

On the same stem a big blowfly has alighted. Judging from appearances,

he has had his fill of good things, and is now making his leisurely

toilet in the peculiar fashion of his kind, rubbing down his back and

wings with his hind legs, twisting his front feet into spirals, and ever

and anon testing the strength of his elastic neck attachment as he

threatens to pull his head from his body.

This worldly act has been progressing for some moments under the gaze of

a big black digger-wasp, who now concludes to cut it short. When at

close range with his prey, the fly suddenly discovers the unhealthy

location which he occupies, and actually protruding his tongue by way of

parting salute, he is off with a buzz. He has barely taken wing,

however, when a still louder buzz is heard, while a great black

bumblebee follows closely in his wake, until the sounds of both are

lost in the distance. The hum of this bumblebee is a frequent musical

feature of the entertainment, and many is the dance that is set to its

minstrelsy, as the burly insect darts in among the merrymakers and is

off to his perch near by. It is only as we steal away and observe him

closely that we learn the secret of his occasional sorties. There on a

clover blossom he sits--sipping honey? Oh no. It is honey-dew that he is

enjoying, and second-hand at that, as he devours the satiated

bluebottle-fly which is empaled on his black horny beak. For this is

only a bumblebee in masquerade--a carnivorous fly, in truth, which, safe

in its disguise of respectability, hovers in the flowery haunts of the

innocents and, of course, reaps his reward.

And what is this? A yellow-jacket has found an ambrosial attraction here

upon the bramble leaf. Meanwhile a great black and white paper-hornet

has seen his opportunity, and is soon slyly approaching behind the

sipper. That he has designs on that jacket and its contents is apparent.

In a moment the onslaught is consummated, and in the struggle which

ensues the black assailant relieves his victim--of his watch presumably,

for he has captured the entire garment, which he soon rifles and

discards with some show of satisfaction.

And so my carnival proceeds. So it began with the dawn; so it will

continue till dusk; and through the night, with new revels, for aught I

know, and will be prolonged for days or weeks.

* * * * *

Reflective reader, how often, as you have strolled through some nook in

the suburban wood, have you paused in philosophic mood at the motley

relics of good cheer which sophisticated the retreat, so pathetically

eloquent of pristine joys to which you had been a stranger? Here in my

present picnic is the suggestive parallel, for even though no such

actual episodes as those I have described had been witnessed by me, an

examination of the premises beneath my bramble were a sufficient

commentary. These were the unimpeachable witnesses of the pleasures

which I have pictured. Dismembered butterfly wings strewed the grassy

jungle, among which were a fair sprinkling from that black and white

halo already noted. Occasional dead wasps and detached members of wasp

and hornet anatomy were frequent, while the blue glitter of the bodies

of flies lit up a shadowy recess here and there, showing that Musca had

not always so correctly gauged his comparative wing resources as my

observation had indicated.

It was interesting to discover, too, down deep among the herbage,

another suggestive fact in the presence of a shrewd spider that showed a

keen eye to the main chance, and had spread his gossamer catch-all

beneath the bramble. It was all grist into his mill, and no doubt his

charnel-house at the base of his silken tunnel could have borne eloquent

testimony alike to his wise sagacity and his epicurean luxury.

I have pictured my picnic, and the question naturally arises, what was

it all about--what the occasion for this celebration? There was

certainly no distinct visible cause for the social gathering upon this

particular bramble-bush. There were a number of other bramble-bushes in

the near neighborhood which, it would seem, should possess equal

attractions, but which were ignored. In what respect did the one

selected differ from the others?

This bramble had become the scene of my carnival simply because it

chanced to be directly beneath an overhanging branch of pine some twenty

feet above. Here dwelt mine host who had issued the invitations and

spread the feast, the limb for about a foot space being surrounded by a

colony of aphides, or plant-lice, from whose distilling pipes the rain

of sweet honey-dew had fallen ceaselessly upon the leaves below. The

flies, butterflies, and ants had been attracted, as always, by its

sweets; the preoccupied convivial flies, in turn, were a tempting bait

for the wasps and hornets, and my dragon-fly and mock bumblebee found a

similar attraction in the neighborhood.

An examination of the trunk of the pine showed the inevitable double

procession of ants, both up and down the tree, with the habitual

interchange of comment; and could we but have obtained a closer glimpse

of the pine branch above, we might certainly have observed the queer

spectacle of the small army of ants interspersed everywhere among the

swarm of aphides. Not in antagonism; indeed, quite the reverse; herders,

in truth, jealously guarding their feeding flock, creeping among them

with careful tread, caressing them with their antennæ while they sipped

at the honeyed pipes everywhere upraised in most expressive and

harmonious welcome.

This intimate and friendly association of the ants and aphides has been

the subject of much interesting scientific investigation and surprising

discovery. Huber and Lubbock have given to the world many startling

facts, the significance of which may be gathered from the one statement

that certain species of ants carry their devotion so far as literally to

cultivate the aphides, carrying them bodily into their tunnels, where

they are placed in underground pens, reared and fed and utilized in a

manner which might well serve as a pattern for the modern dairy farm.

Indeed, after all that we have already seen upon a single bramble-bush,

would it be taking too much license with fact to add one more pictorial

chronicle--an exhilarated and promiscuous group of butterflies, ants,

hornets, wasps, and flies uniting in "a health to the jolly aphis"?

[Illustration]

_A FEW NATIVE ORCHIDS AND THEIR INSECT SPONSORS_

[Illustration]

In a previous article I discussed the general subject of the

fertilization of flowers, briefly outlining the several historical and

chronological steps which ultimately led to Darwin's triumphant

revelation of the divine plan of "cross-fertilization" as the mystery

which had so long been hidden beneath the forms and faces of the

flowers.

In the same paper I presented many illustrative examples among our

common wild flowers possessing marvellous evolved devices, mechanisms,

and peculiarities of form by which this necessary cross-fertilization

was assured.

Prior to Darwin's time the flower was a voice in the wilderness, heard

only in faintest whispers, and by the few. But since his day they have

bloomed with fresher color and more convincing perfume. Science brought

us their message. Demoralizing as it certainly was to humanity's past

ideals, philosophic, theologic, and poetic, it bore the spirit of

absolute conviction, and must be heard.

What a contrast this winged botany of to-day to that of a hundred years

ago! The flower now no longer the mere non-committal, structural,

botanical specimen. No longer the example of mere arbitrary, independent

creation, reverently and solely referred to the orthodox "delight of

man." The blossom whose unhappy fate was bemoaned by the poet because,

forsooth, it must needs "blush unseen," or "waste its sweetness on the

desert air," is found alone in that musty _hortus siccus_ of a blind and

deluded past. From the status of mere arbitrary creation, however

"beautiful," "curious," "eccentric," hitherto accepted alone on

faith--"it is thus because it is created thus: what need to ask the

reason why?"--it has become a part of our inspiring heritage, a

reasonable, logical, comprehensible _result_, a manifestation of a

beautiful divine scheme, and is thus an ever-present witness and prophet

of divine care and supervision.

The flower of to-day! What an inspiration to our reverential study! What

a new revelation is borne upon its perfume! Its forms and hues, what

invitations to our devotion! This spot upon the petal; this peculiar

quality of perfume or odor; this fringe within the throat; this curving

stamen; this slender tube! What a catechism to one who knows that each

and all represent an affinity to some insect, towards whose vital

companionship the flower has been adapting itself through the ages,

looking to its own more certain perpetuation!

The great Linnæus would doubtless have claimed to "know" the "orchid,"

which perhaps he named. Indeed, did he not "know" it to the core of its

physical, if not of its physiological, being? But could he have solved

the riddle of the orchid's persistent refusal to set a pod in the

conservatory? Could he have divined why the orchid blossom continues in

bloom for weeks and weeks in this artificial glazed tropic--perhaps

weeks longer than its more fortunate fellows left behind in their native

haunts--and then only to wither and perish without requital? Know the

orchid?--without the faintest idea of the veritable divorce which its

kidnapping had involved!

Thanks to the new dispensation, we may indeed claim a deeper sympathy

with the flower than is implied in a mere recognition of its pretty

face. We know that this orchid is but the half of itself, as it were;

that its color, its form, however eccentric and incomprehensible, its

twisted inverted position on its individual stalk-like ovary, its

slender nectary, its carefully concealed pollen--all are anticipations

of an insect complement, a long-tongued night-moth perhaps, with whose

life its own is mysteriously linked through the sweet bond of perfume

and nectar, and in the sole hope of posterity.

And the flower had been stolen from its haunt while its consort slept,

and had awakened in a glazed prison--doubtless sufficiently comfortable,

save for the absence of that one indispensable counterpart, towards whom

we behold in the blossom's very being the embodied expression of

welcome.

Blooming day after day in anticipation of his coming, and week after

week still hoping against hope, we see the flower fade upon its stalk,

and with what one might verily believe to be evidences of

disconsolation, were it not that the ultra-scientist objects to such a

sentimental assumption with regard to a flower, which is unfortunate

enough to show no sign of nerves or gray matter in its composition. Who

shall claim to _know_ his orchid who knows not its insect sponsor?

To take one of our own wild species. Here is the _Arethusa bulbosa_ of

Linnæus, for instance. Its pollen must reach its stigma--so he

supposed--in order for the flower to become fruitful. But this is

clearly impossible, as the pollen never leaves its tightly closed box

unless removed by outside aid, which aid must also be required to place

it upon the stigma. This problem, which confronted him in practically

every orchid he met, Linnæus, nor none of his contemporaries, nor indeed

his followers for many years, ever solved.

Not until the time of Christian Conrad Sprengel (1735) did this and

other similar riddles begin to be cleared up, that distinguished

observer having been the first to discover in the honey-sipping insect

the key to the omnipresent mystery. Many flowers, he discovered, were so

constructed or so planned that their pollen could _not_ reach their own

stigmas, as previously believed. The insect, according to Sprengel,

enjoyed the anomalous distinction of having been called in, in the

emergency, to fulfil this apparent default in the plain intentions of

nature, as shown in the flower. Attracted by the color and fragrance of

the blossom, with their implied invitation to the assured feast of

nectar, the insect visited the flower, and thus became dusted with the

pollen, and in creeping or flying out from it conveyed the fecundating

grains to the receptive stigma, which they could not otherwise reach.

Such was Sprengel's belief, which he endeavored to substantiate in an

exhaustive volume containing the result of his observations pursuant to

this theory.

But Sprengel had divined but half the truth. The insect _was necessary_,

it was true, but the Sprengel idea was concerned only with the

_individual_ flower, and the great botanist was soon perplexed and

confounded by an opposing array of facts which completely destroyed the

authority of his work--facts which showed conclusively that the insect

could _not_ thus convey the pollen as described, because the stigma in

the flower was either not yet ready to receive it--perhaps tightly

closed against it--or was past its receptive period, even decidedly

withered.

[Illustration]

This radical assumption of fertilization in the individual flower, which

lay at the base of Sprengel's theory, thus so completely exposed as

false, discredited his entire work. The good was condemned with the bad,

and the noble volume was lost in comparative oblivion--only to be

finally resurrected and its full value and significance revealed by the

keen scientific insight of Darwin (1859). From the new stand-point of

evolution through natural selection the _facts_ in Sprengel's work took

on a most important significance. Darwin now reaffirmed the Sprengel

theory so far as the necessity of the insect was concerned, but showed

that all those perplexing floral conditions which had disproved

Sprengel's assumption, instead of having for their object the conveying

of pollen to the stigma of the _same_ flower, implied its _transfer_ to

the stigma of _another_, cross-fertilization being the evident design,

or evolved and perpetuated advantage.

This solution was made logical and tenable only on the assumption that

such evolved conditions, insuring cross-fertilization, were of distinct

advantage to the flower in the competitive struggle for existence, and

that all cross-fertilized flowers were thus the final result of natural

selection.

The early ancestors of this flower were self-fertilized; a chance

seedling at length, among other continual variations, showed the

singular variation of ripening its stigma in advance of its pollen--or

other condition insuring cross-fertilization--thus acquiring a strain of

fresh vigor. The seedlings of this flower, coming now into competition

with the existing weaker self-fertilized forms, by the increased vigor

won in the struggle of their immediate surroundings, and inheriting the

peculiarity of their parent, showed flowers possessing the same

cross-fertilizing device. The seeds from these, again scattering,

continued the unequal struggle in a larger and larger field and in

increasing numbers, continually crowding out all their less vigorous

competitors of the same species, at length to become entire masters of

the field and the only representatives left to perpetuate the line of

descent.

Thus we find in almost every flower we meet some astonishing development

by which this cross-fertilization is effected, by which the

transferrence of the pollen from one flower to the stigma of another is

assured, largely through the agency of insects, frequently by the wind

and water, occasionally by birds. In many cases this is assured by the

pollen-bearing flowers and stigmatic flowers being entirely distinct,

as in cucumbers and Indian-corn; perhaps on different plants, as in the

palms and willows; again by the pollen maturing and disseminating before

the stigma is mature, as already mentioned, and _vice versa_.

From these, the simplest forms, we pass on to more and more complicated

conditions, anomalies of form and structure--devices, mechanisms, that

are past belief did we not observe them in actuality with our own eyes,

as well as the absolutely convincing demonstration of the intention

embodied: exploding flowers, shooting flowers, flower-traps, stamen

embraces, pollen showers, pollen plasters, pollen necklaces, and floral

pyrotechnics--all demonstrations in the floral etiquette of welcome and

_au revoir_ to insects.

From the simplest and regular types of flowers, as in the buttercup, we

pass on to more and more involved and unsymmetrical forms, as the

columbine, monk's-hood, larkspur, aristolochia, and thus finally to the

most highly specialized or involved forms of all, as seen in the

orchid--the multifarious, multiversant orchid; the beautiful orchid; the

ugly orchid; the fragrant orchid; the fetid orchid; the graceful,

homely, grotesque, uncanny, mimetic, and, until the year 1859, the

absolutely non-committal and inexplicable flower; the blossom which had

waited through the ages for Darwin, its chosen interpreter, ere she

yielded her secret to humanity.

And what is an orchid? How are we to know that this blossom which we

plucked is an orchid? The average reader will exclaim, "Because it is an

air-plant"--the essential requisite, it would seem, in the popular mind.

Of over 3000 known species of orchids, it is true a great majority are

air-plants, or epiphytes--growing upon trees and other plants, obtaining

their sustenance from the air, and not truly parasitic; but of the

fifty-odd native species of the northeastern United States, not one is

of this character, all growing in the ground, like other plants. It is

only by the botanical structure of the flowers that the orchid may be

readily distinguished, the epiphytic character being of little

significance botanically.

A brief glance at this structural peculiarity may properly precede our

more elaborate consideration of a few species of these remarkable

flowers.

The orchids are usually very irregular, and six-parted. The ovary is

one-celled, and becomes a pod containing an enormous yield of minute,

almost spore-like, seeds (Fig. 3) in some species, as in the vanilla

pod, to the number of a million, and in one species of the maxillaria,

as has been carefully computed, 1,750,000.

The pollen, unlike ordinary flowers, is gathered together in waxy masses

of varying consistency, variously formed and disposed in the blossom,

its grains being connected with elastic cobwebby threads, which

occasionally permit the entire mass to be stretched to four or five

times its length, and recover its original shape when released. This is

noticeable specially in the _O. spectabilis_, later described. The

grains thus united are readily disentangled from their mass when brought

into contact with a viscid object, as, for instance, the stigma.

[Illustration: Fig. 1]

But the most significant botanical contrast and distinction is found in

the union of the style and stamens in one organ, called the column (Fig.

2), the stigma and the pollen being thus disposed upon a single common

stalk. The contrast to the ordinary flower will be readily appreciated

by comparison of the accompanying diagrams (Fig. 1).

When, therefore, we find a blossom with the anthers or pollen

receptacle united to a stalk upon which the stigma is also placed, we

have an orchid.

The order is further remarkable, as Darwin first demonstrated in his

wonderful volume "The Fertilization of Orchids," in that the entire

group, with very few exceptions, are absolutely dependent upon insects

for their perpetuation through seed. They possess no possible resource

for self-fertilization in the neglect of these insect sponsors.

[Illustration: Fig. 2 a. Anther. s. Stigma.]

Many of our common wild flowers, as perfectly and effectually planned

for cross-fertilization as the orchids, _do_ retain the reserve power of

final _self_-fertilization if unfertilized by foreign pollen.

But the orchid has lost such power, and in the progress of evolution has

gradually adapted itself to the insect, often to a particular species of

insect, its sole sponsor, which natural selection has again gradually

modified in relation to the flower.

The above work by Darwin was mostly concerned with foreign species,

generally under artificial cultivation, and so startling were the

disclosures concerning these hitherto sphinx-like floral beings that a

most extensive bibliography soon attested the widespread inspiration and

interest awakened by its pages.

But it is by no means necessary to visit the tropics or the conservatory

for examples of these wonders. Our own Asa Gray, one of Darwin's instant

proselytes, was prompt to demonstrate that the commonest of our native

American species might afford revelations quite as astonishing as those

exotic species which Darwin had described.

[Illustration: Fig. 3]

During a period of many years the writer has devoted much study to our

native species of orchids from this evolutionary stand-point of their

cross-fertilization tendencies. Of the following examples, selected from

his list, some are elaborations of previous descriptions of Gray and

others, though pictorially and descriptively the result of direct

original study from nature; others are from actual observation of the

insects at work on the flowers; and others still, original

demonstrations based upon analogy and the obvious intention of the

floral construction, the action of the insect--its head or

tongue--having been artificially imitated by pins, bristles, or other

probe-like bodies.

How many an enthusiastic flower-hunter has plucked his fragrant bouquet

of the beautiful Arethusa, in its sedgy haunt, without a suspicion of

the beautiful secret which lay beneath its singular form! Indeed, how

many a learned botanist, long perfectly familiar with its peculiarities

of shape and structure, has been entirely content with this simple fact,

nor cared to seek further for its interpretation! But

"All may have the flower now,

For all have got the seed."

With Darwin as our guide and the insect as our key--an _open

sesame_--the hidden treasure is revealed. It is now quite possible, as

Darwin demonstrated, to look upon a flower for the first time and from

its structure foretell the method of its intended cross-fertilization;

nay, more, possibly the kind, or even the species, of insect to which

this cross-fertilization is intrusted.

Let us look at our Arethusa. The writer has never happened to observe an

insect at work upon this flower, but the intention of its structure is

so plain that by a mere examination we may safely prophesy not only what

must happen when the insect seeks its nectar, but with equal assurance

the kind of insect thus invited and expected. I have indicated a group

of the orchids in their usual marshy haunt, and in Fig. 4, separately, a

series of diagrams presents sections of the flower, natural size and

duly indexed, which renders detailed description hardly necessary. The

column is here quite elongated, forked at the tip, the space between the

forks occupied by the anther, which is hinged to the upper division.

This anther lid is closed tightly, with the sticky mass of pollen hidden

behind it in the cavity. The stigma is on the external inner side of the

lower division, and thus distinctly separated from the pollen. The "lip"

is extended forward as a hospitable threshold to the insect. And to what

insect might we assume this invitation of color, fragrance, nectar, and

threshold to be extended?

Let us consider the flower simply as a device to insure its own

cross-fertilization. The insect is welcomed; it must alight and sip the

nectar; in departing it must bear away this pollen upon its body, and

convey it to the _next_ Arethusa blossom which it visits, and leave it

upon its stigma. These are the conditions expressed; and how admirably

they are fulfilled we may observe when we examine flower after flower of

a group, and find their nectaries drained, their anther cells empty, and

pollen upon all their stigmas. The nectar is here secreted in a

well--not very deep--and the depth of this nectar from the entrance is

of great significance among all the flowers, having distinct reference

to the length of the tongue which is expected to sip it. In the

Arethusa, it is true, the butterfly or moth might sip at the throat of

the flower, but the long tongues of these insects might permit the

nectary to be drained without bringing their bodies in contact with the

stigma. Smaller insects might creep into the nectary and sip without the

intended fulfilment. It is clear that to neither of such visitors is the

welcome extended. What, then, are the conditions embodied? The insect

must have a tongue of such a length that, when in the act of sipping,

its head must pass beyond the anther well into the opening of the

flower. Its body must be sufficiently large to come in contact with the

anther. Such requisites are perfectly fulfilled by the humblebee, and

we may well hazard the prophecy that the Bombus is the welcomed affinity

of the flower.

[Illustration: Fig. 4]

The diagrams (Fig. 4) sufficiently illustrate the efficacy of the

beautiful plan involved. At A the bee is seen sipping the nectar. His

forward movement thus far to this point has only seemed to press the

edge of the anther inward, and thus keep it even more effectually

closed. As the bee retires (B), the backward motion opens the lid, and

the sticky pollen is thus brought against the insect's back, where it

adheres in a solid mass. He now flies to the next Arethusa blossom,

enters it as before, and in retiring slides his back against the

receptive viscid stigma, which retains a portion of the pollen, and thus

effects the cross-fertilization (C). Professor Gray surmised that the

pollen was withdrawn on the insect's head, and it might be so withdrawn,

but in other allied orchids of the tribe Arethusæ, however, in which the

structure is very similar, the pollen is deposited on the thorax, and

such is probably the fact in this species. In either case

cross-fertilization would be effected. Nothing else is possible in the

flower, and whether it is Bombus or not that effects it, the method is

sufficiently evident.

Having thus had one initiation into this most enticing realm of riddles,

each successive orchid whose structure we examine from this stand-point

becomes a most interesting, perhaps a fresh, problem, whose assumed

solution may often be verified by studying the insect in its haunts.

Darwin thus foretold the precise manner of the cross-fertilization of

_Habenaria mascula_, and also the insect agent, simply by the structural

prophecy of the flower itself.

Suppose, for example, an unknown orchid blossom to be placed in our

hands. Its nectary tube is five inches in length, and as slender as a

knitting-needle. The nectar is secreted far within its lip. The

evolution of the long nectary implies an adaptation to an insect's

tongue of equal length. What insect has a tongue five inches long, and

sufficiently slender to probe this nectary? The sphinx-moth only. Hence

we infer the sphinx-moth to be the insect complement to the blossom, and

we may correctly infer, moreover, that the flower is thus a

night-bloomer. Examination of the flower, with the form of this moth in

mind, will show other adaptations to the insect's form in the position

of pollen and stigma, looking to the flower's cross-fertilization. In

some cases this is effected by the aid of the insect's tongue; in

others, by its eyes.

In our own native orchids we have a remarkable example of the latter

form in the _Habenaria orbiculata_, whose structure and mechanism have

also been admirably described by Asa Gray.

[Illustration: Fig. 5]

All orchid-hunters know this most exceptional example of our local

flora, and the thrill of delight experienced when one first encounters

it in the mountain wilderness, its typical haunt, is an event to date

from--its two great, glistening, fluted leaves, sometimes as large as

a dinner-plate, spreading flat upon the mould, and surmounted by the

slender leafless stalk, with its terminal loose raceme of greenish-white

bloom.

[Illustration]

A single blossom of the species is shown in Fig. 5, the parts indexed.

The opening to the nectary is seen just below the stigmatic surface, the

nectary itself being nearly two inches in length. The pollen is in two

club-like bodies, each hidden within a fissured pouch on either side of

the stigma, and coming to the surface at the base in their opposing

sticky discs as shown. Many of the group Habenaria or Platanthera, to

which this flower belongs, are similarly planned. But mark the

peculiarly logical association of the parts here exhibited. The nectary

implies a welcome to a tongue two inches long, and will reward none

other. This clearly shuts out the bees, butterflies, and smaller moths.

What insect, then, is here implied? The sphinx-moth again, one of the

lesser of the group. A larger individual might sip the nectar, it is

true, but its longer tongue would reach the base of the tube without

effecting the slightest contact with the pollen, which is of course the

desideratum here embodied, and which has reference to a tongue

corresponding to the length of the nectary. There are many of these

smaller sphinxes. Let us suppose one to be hovering at the blossom's

throat. Its slender capillary tongue enters the opening. Ere it can

reach the sweets the insect's head must be forced well into the throat

of the blossom, where we now observe a most remarkable special

provision, the space between the two pollen discs being exactly adjusted

to the diameter of the insect's head. What follows this entrance of the

moth is plainly pictured in the progressive series of illustrations

(Fig. 6). A represents the insect sipping; the sticky discs are brought

in contact with the moth's eyes, to which they adhere, and by which they

are withdrawn from their pouches as the moth departs (B). At this time

they are in the upright position shown at C, but in a few seconds bend

determinedly downward and slightly towards each other to the position D.

This change takes place as the moth is flitting from flower to flower.

At E we see the moth with its tongue entering the nectary of a

subsequent blossom. By the new position of the pollen clubs they are now

forced directly against the stigma (E). This surface is viscid, and as

the insect leaves the blossom retains the grains in contact (F), which

in turn withdraw others from the mass by means of the cobwebby threads

by which the pollen grains are continuously attached. At G we see the

orchid after the moth's visit--the stigma covered with pollen, and the

flower thus cross-fertilized.

[Illustration: Fig. 6]

In effecting the cross-fertilization of one of the younger flowers its

eyes are again brought into contact with this second pair of discs, and

these, with their pollen clubs, are in turn withdrawn, at length perhaps

resulting in such a plastering of the insect's eyes as might seriously

impair its vision, were it not fortunately of the compound sort.

In another allied example of the orchids--the Showy Orchid--we have,

however, what would appear a clear adaptation to the head of a bee,

though one which might also avail of the service of an occasional

butterfly. A group of this beautiful species is shown in my

illustration. A favored haunt is the dark damp woods, especially beneath

hemlocks, and with its deep pink hood and pure white lip is quite showy

enough to warrant its specific title, "spectabilis." An enlarged view of

the blossom is seen in Fig. 7, and in Fig. 8 a still greater enlargement

of the column.

[Illustration: Fig. 7]

[Illustration: Fig. 8 A, Pollinium. B, Webby connection between grains. C,

Stretched to four times its length.]

I have seen many specimens with the pollen masses withdrawn, and others

with their stigmas well covered with the grains. Though I have never

seen an insect at work upon it in its haunt, the whole form of the

opening of the flower would seem to imply a bee, particularly a

bumblebee. If we insert the point of a lead-pencil into this opening,

thus imitating the entrance of a bee, its bevelled surface comes in

contact with the viscid discs by the rupture of a veil of membrane,

which has hitherto protected them. The discs adhere to the pencil, and

are withdrawn upon it (Fig. 9). At first in upright position, they soon

assume the forward inclination, as previously described. The nectary is

about the length of a bumblebee's tongue, and is, moreover, so amply

expanded at the throat below the stigma as to comfortably admit its

wedge-shaped head. The three progressive diagrams (Fig. 10) indicate the

result in the event of such a visit.

The pollen discs are here very close together, and are protected within

a membraneous cup, in which they sit as in a socket. As the insect

inserts his head at the opening (A) it is brought against this tender

membrane, which ruptures and exposes the viscid glands of the pollen

masses, which become instantly attached to the face or head, perhaps

the eyes, of the burly visitor. As the insect retreats from the flower,

one or both of the pollinia are withdrawn, as at B. Then immediately

follows a downward movement, which exactly anticipates the position of

the stigma, and as the bee enters the next flower the pollen clubs are

forced against it (C), as in the previous example.

[Illustration: Fig. 9]

In the case of a smaller bee visiting the flower, the insect would find

it necessary to creep further into the opening, and thus might bring its

thorax against the pollen-glands. In either case the change of position

in the pollinia would insure the same result.

[Illustration: Fig. 10 A B]

We have thus seen adaptation to the thorax, the eyes, and the face in

the three examples given. And the entrance of the flower in each

instance is so formed as to insure the proper angle of approach for the

insect for the accomplishment of the desired result. This direct

approach, so necessary in many orchids, is insured by various

devices--by the position of the lip upon which the insect must alight;

by the narrowed entrance of the throat of the flower in front of the

nectary; by a fissure in the centre of the lip, by which the tongue is

conducted, etc.

[Illustration: Fig. 10 C]

Many other species allied to the above possess similar devices, with

slight variations; and there is still another group whose structure is

distinctly adjusted to the _tongues_ of insects--adaptations not merely

of position of pollen masses, but even to the extent of a special

modification in the entrance to the flower and the shape of the sticky

gland, by which it may more securely adhere to that sipping member.

In the common pretty Purple-fringed Orchid, whose dense cylindrical

spikes of plumy blossoms occasionally empurple whole marshes, we have an

arrangement quite similar to the _H. orbicularis_ just described, with

the exception that the pollen-pouches are almost parallel, and not

noticeably spread at the base (Fig. 11). In this case the eyes of

sipping butterflies occasionally get their decoration of a tiny golden

club, but more frequently their tongues.

[Illustration: Fig. 11]

If, however, the butterfly should approach directly in front of the

flower, as in a larger blossom he would be most apt to do, he might sip

the nectar indefinitely and withdraw his tongue without bringing it in

contact with the viscid pollen discs. But in the dense crowding of the

flowers, over which the insect flutters indiscriminately, the approach

is oftenest made obliquely, and thus the tongue brushes the disc on the

side approached, and the pollen mass is withdrawn. But an examination of

this orchid affords no pronounced evidence of any specific intention.

There is no unmistakable sign to demonstrate which approach is

preferred or designed by the flower, and this dependence on the insect's

tongue or eye would seem to be left to chance.

In another closely allied species, however, we have a distinct provision

which insures the proper approach of the tongue--one of many similar

devices by which the tongue is conducted directly to one or the other of

the pollen discs.

[Illustration: Fig. 12]

This is the Ragged Orchid, a near relative of the foregoing, _H.

psycodes_, but far less fortunate in its attributes of beauty, its long

scattered spike of greenish-white flowers being so inconspicuous in its

sedgy haunt as often to conceal the fact of its frequency. Its

individual flower is shown enlarged at Fig. 12--the lip here cut with a

lacerated fringe (_H. lacera_). The pollen-pouches approach slightly at

the base, directly opposite the nectary, where the two viscid

pollen-glands stand on guard. Now were the opening of the nectary at

this point unimpeded, the same condition would exist as in the _H.

psycodes_--the tongue might be inserted between the pollen discs and

withdrawn without touching them. But here comes the remarkable and very

exceptional provision to make this contact a certainty--a

suggestive structural feature of this flower of which I am surprised

to find no mention either in our botanies or in the literature of

cross-fertilization, so far as I am familiar with its bibliography. Even

Dr. Gray's description of the fertilization device of this species makes

no mention of this singular and very important feature. The nectary

here, instead of being freely open, as in other orchids described, is

abruptly closed at the central portion by a firm protuberance or palate,

which projects downward from the base of the stigma, and closely meets

the lip below.

The throat of the nectary, thus centrally divided, presents two small

lateral openings, each of which, from the line of approach through the

much-narrowed entrance of the flower, is thus brought directly beneath

the waiting disc upon the same side. The structure is easily understood

from the two diagrams Figs. 12 and 13, both of which are indexed.

The viscid pollen-gland is here very peculiarly formed, elongated and

pointed at each end, and it is not until we witness the act of its

removal on the tongue of the butterfly that we can fully appreciate its

significance.

I have often seen butterflies at work upon this orchid, and have

observed their tongues generously decorated with the glands and remnants

of the pollen masses.

[Illustration: Fig. 13]

The series of diagrams (Fig. 14) will, I think, fully demonstrate how

this blossom utilizes the butterfly. At A we see the insect sipping, its

tongue now in contact with the elongated disc, which adheres to and

clasps it. The withdrawal of the tongue (B) removes the pollen from its

pouch. At C it is seen entirely free and upright, from which position it

quickly assumes the new attitude shown at D. As the tongue is now

inserted into the subsequent blossom this pollen mass is thrust against

the stigma (E), and a few of the pollen grains are thus withheld upon

its viscid surface as the insect departs (F).

In this orchid we thus find a distinct adaptation to the tongue of a

moth or butterfly.

Another similar device for assuring the necessary side approach is seen

in _H. flava_ (Fig. 15), a yellowish spiked species, more or less common

in swamps and rich alluvial haunts.

[Illustration: Fig. 14]

Professor Wood remarks, botanically, "The tubercle (or palate) of the

lip is a remarkable character." But he, too, has failed to note the

equally remarkable palate of the ragged orchid, just described, both

provisions having the same purpose, the insurance of an oblique approach

to the nectary. In _H. flava_ this "tubercle," instead of depending

from the throat, grows _upward_ from the lip, and, as we look at the

flower directly from the front, completely hides the opening to the

nectary, and an insect is compelled to insert its tongue on one side,

which direction causes it to pass directly beneath the pollen disc, as

in _H. lacera_, and with the same result.

[Illustration: Fig. 15]

Of all our native orchids, at least in the northeastern United States,

the Cypripedium, or Moccasin-Flower, is perhaps the general favorite,

and certainly the most widely known. This is readily accounted for not

only by its frequency, but by its conspicuousness. The term

"moccasin-flower" is applied more or less indiscriminately to all

species. The flower is also known as the ladies'-slipper, more

specifically Venus's-slipper--as warranted by its generic botanical

title--from a fancied resemblance in the form of the inflated lip, which

is characteristic of the genus. We may readily infer that the fair

goddess was not consulted at the christening.

[Illustration]

There are six native species of the cypripedium in this Eastern region,

varying in shape and in color--shades of white, yellow, crimson, and

pink. The mechanism of their cross-fertilization is the same in all,

with only slight modifications.

The most common of the group, the _C. acaule_, most widely known as the

moccasin-flower, whose large, nodding, pale crimson blooms we so

irresistibly associate with the cool hemlock woods, will afford a good

illustration.

The lip in all the cypripediums is more or less sac-like and inflated.

In the present species, _C. acaule_, however, we see a unique variation,

this portion of the flower being conspicuously bag-like, and cleft by a

fissure down its entire anterior face. In Fig. 16 is shown a front view

of the blossom, showing this fissure. The "column" (B) in the

cypripedium is very distinctive, and from the front view is very

non-committal. It is only as we see it in side section, or from beneath,

that we fully comprehend the disposition of stigma and pollen. Upon the

stalk of this column there appear from the front three lobes--two small

ones at the sides, each of which hides an anther attached to its under

face--the large terminal third lobe being in truth a barren rudiment of

a former stamen, and which now overarches the stigma. The relative

position of these parts may be seen in the under view.

[Illustration]

The anthers in this genus, then, are two, instead of the previous

single anther with its two pollen-cells. The pollen is also quite

different in its character, being here in the form of a pasty mass,

whose entire exposed surface, as the anther opens, is coated with a very

viscid gluten.

[Illustration: Fig. 16]

With the several figures illustrating the cross-fertilization, the

reader will readily anticipate any description of the process, and only

a brief commentary will be required in my text.

I have repeatedly examined the flowers of _C. acaule_ in their haunts,

have observed groups wherein every flower still retained its pollen,

others where one or both pollen masses had been withdrawn, and in

several instances associated with them I have observed the inflated lip

most outrageously bruised, torn, and battered, and occasionally

perforated by a large hole. I had observed these facts in boyhood. The

inference, of course, was that some insect had been guilty of the

mutilation; but not until I read Darwin's description of the

cross-fertilization of this species did I realize the full significance

of these telltale evidences of the escape of the imprisoned insect.

Since that time, many years ago, I have often sat long and patiently in

the haunt of the cypripedium awaiting a natural demonstration of its

cross-fertilization, but as yet no insect has rewarded my devotion.

[Illustration: Fig. 17]

At length, in hopelessness of reward by such means, I determined to see

the process by more prosaic methods. Gathering a cluster of the freshly

opened flowers, which still retained their pollen, I took them to my

studio. I then captured a bumblebee, and forcibly persuaded him to enact

the demonstration which I had so long waited for him peaceably to

fulfil. Taking him by the wings, I pushed him into the fissure by which

he is naturally supposed to enter without persuasion. He was soon within

the sac, and the inflexed wings of the margin had closed above him, as

shown in section, Fig. 17. He is now enclosed in a luminous prison, and

his buzzing protests are audible and his vehemence visible from the

outside of the sac. Let us suppose that he at length has become

reconciled to his condition, and has determined to rationally fulfil the

ideal of his environment, as he may perhaps have already done

voluntarily before. The buzzing ceases, and our bee is now finding sweet

solace for his incarceration in the copious nectar which he finds

secreted among the fringy hairs in the upper narrowed portion of the

flower, as shown at Fig. 18 A. Having satiated his appetite, he

concludes to quit his close quarters. After a few moments of more

vehement futile struggling and buzzing, he at length espies, through the

passage above the nectary fringe, a gleaming light, as from two windows

(A). Towards these he now approaches. As he advances the passage becomes

narrower and narrower, until at length his back is brought against the

overhanging stigma (Fig. 18 B). So narrow is the pass at this point that

the efforts of the bee are distinctly manifest from the outside in the

distension of the part and the consequent slight change in the droop of

the lip. In another moment he has passed this ordeal, and his head is

seen protruding from the window-like opening (A) on one side of the

column. But his struggles are not yet ended, for his egress is still

slightly checked by the narrow dimensions of the opening, and also by

the detention of the anther, which his thorax has now encountered. A

strange etiquette this of the cypripedium, which speeds its parting

guest with a sticky plaster smeared all over its back. As the insect

works its way beneath the viscid contact, the anther is seen to be drawn

outward upon its hinge, and its yellow contents are spread upon the

insect's back (Fig. 18 C), verily like a plaster. Catching our bee

before he has a chance to escape with his generous floral compliments,

we unceremoniously introduce him into another cypripedium blossom, to

which, if he were more obliging, he would naturally fly. He loses no

time in profiting by his past experience, and is quickly creeping the

gantlet, as it were, or braving the needle's eye of this narrow passage.

His pollen-smeared thorax is soon crowding beneath the overhanging

stigma again, whose forward-pointed papillæ scrape off a portion of it

(Fig. 18 B), thus insuring the cross-fertilizing of the flower, the bee

receiving a fresh effusion of cypripedium compliments piled upon the

first as he says "good-bye." It is doubtful whether in his natural life

he ever fully effaces the telltale effects of this demonstrative _au

revoir_.

[Illustration: Fig. 18 A]

Such, with slight modifications, is the plan evolved by the whole

cypripedium tribe. Darwin mentions bees as the implied fertilizers, and

doubtless many of the smaller bees do effect cross-fertilization in the

smaller species. But the more ample passage in acaule would suggest the

medium-sized Bombus as better adapted--as the experiment herewith

pictured from my own experience many times would seem to verify, while a

honey-bee introduced into the flower failed to fulfil the demonstration,

emerging at the little doorway above without a sign of the cordial

parting token.

[Illustration: Fig. 18 B]

Occasionally I suppose a fool bumblebee is entrapped within the petal

bower and fails to find the proper exit, or it may be--much less a

fool--having run the gantlet once too often, decides to escape the

ordeal; hence the occasional mutilated blossom already described.

One of the most beautiful of our orchids, though its claims to

admiration in this instance are chiefly confined to the foliage, is the

common "Rattlesnake-Plantain," its prostrate rosettes of exquisitely

white reticulated leaves carpeting many a nook in the shadows of the

hemlocks, its dense spikes of yellowish-white blossoms signalling their

welcome to the bees, and fully compensating in interest what they may

lack in other attractive attributes.

[Illustration: Fig. 18 C]

The single flower is shown enlarged in Fig. 19--A, a young blossom, with

analyses B and C, the latter indexed; D, an older blossom, with similar

analyses (E and F). Both sorts are to be found upon every spike of

bloom, as the inflorescence begins at the base and proceeds upward. As

we look into the more open flower we observe a dark-colored speck,

which, by analysis, proves to be the lid of the anther. This portion is

further shown enlarged in Fig. 20, A. If we gently lift it with a pin,

we disclose the pollen masses in the cavity (B) thus opened (C, profile

section), the two pairs united to a common viscid gland at the base,

this gland again secreted behind a veil of moist membrane, as also shown

at B. This membrane is, moreover, very sensitive to the touch. Below the

flattened tip of the column, and at a sharp inward angle, is the stigma.

In the freshly opened flower (Fig. 19, A) the column inclines forward,

bringing the anther low down, and its base directly opposite the

V-shaped orifice in the lip, which also is quite firmly closed beneath

the equally converging upper hood of the blossom. The entrance is thus

much narrowed. If we insert a pin in this V-shaped entrance it comes in

contact with the sensitive membrane below the anther, and it is

immediately ruptured, as shown at Fig. 20, D. The sticky gland is

brought into immediate contact, and clasps the pin, which, now being

withdrawn, brings away the pollen, as in E and F. Thus it is naturally

removed on the tongue of its sipping bee.

[Illustration: Fig. 19]

[Illustration: Fig. 21]

The further demonstration will be better shown by profile sections (Fig.

21). Nectar is secreted in the hollow of the lip indicated, somewhat as

in the cypripedium. If we now imitate with a probe the habit of the

insect and the action of its tongue, we may witness a beautiful

contrivance for cross-fertilization. We will suppose the bee to be

working at the top of the spike. He thrusts his tongue into the narrow

opening (G). The membrane protecting the pollen-gland, thus surely

touched, ruptures as described, and the exposed gland attaches itself to

the tongue, being withdrawn as at H, and located on the insect's tongue,

as in F, Fig. 20. The bee leaves this flower cluster and flies to

another, upon which it will usually begin operation at the bottom. The

flower thus first encountered is an old bloom, as in Fig. 19, D. Its

sepals are more spreading, the lip slightly lowered, and the column so

changed as to present the plane of the stigma, before out of sight, in

such a new position as to invariably receive the pollen. The tongue of a

bee entering this flower conveys the pollen directly against the

stigmatic surface (I), which retains its disentangled fecundating

grains, as at J, and the flower's functional adaptations are fulfilled.

[Illustration: Fig. 20]

[Illustration: A. Extended. B. Folded beneath the head.]

In the allied Spiranthes, or "Lady's-Tresses," a somewhat similar

mechanism prevails, by which fertilization is largely effected by the

changed position or angle of the stigma plane.

And thus we might proceed through all the orchid genera, each new

device, though based upon one of the foregoing plans, affording its new

surprise in its special modification in adaptation to its insect

sponsor--all these various shapes, folds of petals, positions, colors,

the size, length, and thickness of nectary, the relative positions of

pollen and stigma, embodying an expression of welcome to the insect with

which its life is so marvellously linked. Occasionally this astounding

affinity is faithful to a single species of insect, which thus becomes

the sole sponsor of the blossom, without whose association the orchid

would become extinct. A remarkable instance of this special adaptation

is seen in the great Angræcum orchid of Madagascar, described by Darwin;

and inasmuch as this species glorifies Darwin's faith in the truth of

his theory, and marks a notable victory in the long battle for its

supremacy, it affords an inspiring theme for my closing paragraphs.

Among the host of sceptics--and were they not legion?--who met this

evolutionary and revolutionary theory with incredulity, not to say

ridicule or worse, was one who thus challenged its author shortly after

the appearance of his "Fertilization of Orchids," addressing Darwin from

Madagascar substantially as follows: "Upon your theory of evolution

through natural selection all the various contrasting structural

features of the orchids have direct reference to some insect which shall

best cross-fertilize them. If an orchid has a nectary one inch long, an

insect's tongue of equivalent length is implied; a nectary six inches in

length likewise implies a tongue six inches long. What have you to say

in regard to an orchid which flourishes here in Madagascar possessing a

long nectary as slender as a knitting-needle and eleven inches in

length? On your hypothesis there must be a moth with a tongue eleven

inches long, or this nectary would never have been elaborated."

Darwin's reply was magnificent in its proof of the sublime conviction of

the truth of his belief: "The existence of an orchid with a slender

nectary eleven inches in length, and with nectar secreted at its tip, is

a conclusive demonstration of the existence of a moth with a tongue

eleven inches in length, _even though no such moth is known_."

Many of us remember the ridicule which was heaped upon him for this

apparently blind adherence to an untenable theory. But victory complete

and demoralizing to his opponents awaited this oracular utterance when

later a disciple of Darwin, led by the same spirit of faith and

conviction, visited Madagascar, and was soon able to affirm that he had

caught the moth, a huge sphinx-moth, and that its tongue measured eleven

inches in length.

[Illustration]

Here we see the prophecy of the existence of an unknown moth, founded on

the form of a blossom. At that time the moth had not been actually seen

at work on the orchid, but who shall question for a moment that had

the flower been visited in its twilight or moonlight haunt the murmur of

humming wings about the blossom's throat would have attested the

presence of the flower's affinity, for without the kiss of this

identical moth the Angræcum must become extinct. No other moth can

fulfil the conditions necessary to its perpetuation. The floral

adaptation is such that the moth must force its large head far into the

opening of the blossom in order to reach the sweets in the long nectary.

In so doing the pollen becomes attached to the base of the tongue, and

is withdrawn as the insect leaves the flower, and is thrust against the

stigma in the next blossom visited. This was clearly demonstrated by

Darwin in specimens sent to him, by means of a probe of the presumable

length and diameter of the moth's tongue. Shorter-tongued moths would

fail to remove the pollen, and also to reach the nectar, and would thus

soon learn to realize that they were not welcome.

The Angræcum also affords in this long pendent nectary a most lucid

illustration of the present workings of natural selection. The normal

length of that nectary should be about eleven inches, but in fact this

length varies considerably in the flowers of different plants, this

tendency to variation in all organic life being an essential and amply

demonstrated postulate of the entire theory of natural selection. Let us

suppose a flower whose nectary chances to be only six inches in length.

The moth visits this flower, but the tip of its tongue reaches the

nectar long before it can bring its head into the opening of the tube.

This being a vital condition, the moth fails to withdraw the pollen; and

inasmuch as the pollen is usually deposited close to the head of the

moth, this flower would _receive_ no pollen upon its stigma. This

particular blossom would thus be both barren and sterile. None of its

pollen would be carried to other stigmas, nor would it set a seed to

perpetuate by inheritance its shorter nectary.

Again, let us suppose the variation of an extra long nectary, and the

writer recently saw a number of these orchids with nectaries thirteen

inches in length. The moth comes, and now must needs insert its head to

the utmost into the opening of the flower. This would insure its

fertilization by the pollen on the insect's tongue; and even though the

sipper _failed_ to reach the nectar, the pollen would be withdrawn upon

the tongue, to be carried to other flowers, which might thus be expected

to inherit from the paternal side the tendency to the _longer_ nectary.

The tendency towards the perpetuation of the short nectary is therefore

stopped, while that of the longer nectary is insured.

_THE MILKWEED_

The singular hospitality of our milkweed blossom is nowhere matched

among Flora's minions, and would seem occasionally in need of

supervision.

Just outside the door here at my country studio, almost in touch of its

threshold, year after year there blooms a large clump of milkweed

(_Asclepias cornuta_), and, what with the fragrance of its purple

pompons and the murmurous music of its bees, its fortnight of bloom is

not permitted to be forgotten for a moment. Only a moment ago a whiff of

more than usual redolence from the open window at which I am sitting

reminded me that the flowers were even now in the heyday of their prime,

and the loud droning music betokened that the bees were making the most

of their opportunities.

Yielding to the temptation, I was soon standing in the midst of the

plants. The purple fragrant umbels of bloom hung close about me on all

sides, each flower, with its five generous horns of plenty, drained

over and over again by the eager sipping swarm.

But the July sun is one thing to a bee and quite another thing to me. I

have lingered long enough, however, to witness again the beautiful

reciprocity, and to realize anew, with awe and reverence, how divinely

well the milkweed and the bee understand each other. After a brief

search among the blossom clusters I return to my seclusion with a few

interesting specimens, which may serve as a text here at my desk by the

open window.

Two months hence an occasional silky messenger will float away from the

glistening clouds about the open milkweed pods, but who ever thanks the

bees of June for them? The flower is but a bright anticipation--an

expression of hope in the being of the parent plant. It has but one

mission. All its fragrance, all its nectar, all its beauty of form and

hue are but means towards the consummation of the eternal edict of

creation--"Increase and multiply." To that end we owe all the infinite

forms, designs, tints, decorations, perfumes, mechanisms, and other

seemingly inexplicable attributes. Its threshold must bear its own

peculiar welcome to its insect, or perhaps to its humming-bird friend,

or counterpart; its nectaries must both tempt and reward his coming,

and its petals assist his comfortable tarrying.

Next to the floral orchids, the mechanism of our milkweed blossom is

perhaps the most complex and remarkable, and illustrates as perfectly as

any of the orchid examples given in Darwin's noble work the absolute

divine intention of the dependence of a plant species upon the visits of

an insect.

Our milkweed flower is a deeply planned contrivance to insure such an

end. It fills the air with enticing fragrance. Its nectaries are stored

with sweets, and I fancy each opening bud keenly alert with conscious

solicitude for its affinity. Though many other flowers manage

imperfectly to perpetuate their kind in the default of insect

intervention, the milkweed, like most of the orchids, is helpless and

incapable of such resource. Inclose this budded umbel in tarlatan gauze

and it will bloom days after its fellow-blooms have fallen, anticipating

its consummation, but no pods will be seen upon this cluster.

What a singular decree has Nature declared with reference to the

milkweed! She says, in plainest terms, "Your pollen must be removed on

the leg of an insect, preferably a bee, or your kind shall perish from

the face of the earth." And what is the deep-laid plan by which this

end is assured? My specimens here on the desk will disclose it all.

Here are two bees, a fly, and a beetle, each hanging dead by its legs

from a flower, an extreme sacrificial penalty, which is singularly

frequent, but which was certainly not exacted nor contemplated in the

design of the flower. A careful search among almost any good-sized

cluster of milkweeds will show us many such prisoners. As in all

flowers, the pollen of the milkweed blossom must come in contact with

its stigma before fruition is possible. In this peculiar family of

plants, however, the pollen is distinct in character, and closely

suggests the orchids in its consistency and disposition. The yellow

powdery substance with which we are all familiar in ordinary flowers is

here absent, the pollen being collected in two club-shaped or, more

properly, spatula-shaped masses, linked in pairs at their slender

prolonged tips, each of which terminates in a sticky disc-shaped

appendage united in V-shape below. These pollen masses are concealed in

pockets (B) around the cylindrical centre of the flower, the discs only

being exposed at the surface, at five equidistant points around its rim,

where they lie in wait for the first unwary foot that shall touch

them. A glance at the two views of this central portion of the flower,

as it appears through my magnifying-glass--the honey-horns and sepals

having been removed--will, I think, indicate its peculiar anatomy or

mechanism. No _stigma_ is to be seen in the flower, the stigmatic

surface which is to receive the pollen being concealed within five

compartments, each of which is protected by a raised tent-like covering,

cleft along its entire apex by a fine fissure (A). _Outside of each of

these, and entirely separated from the stigma in the cavity_, lie the

pollen masses within their pockets, each pair uniting at the rim below

in V-shape, the union at the lower limit of the fissure.

[Illustration]

[Illustration]

With this more intimate knowledge of the floral anatomy, let us now

visit our milkweed-plant and observe closely.

A bee alights upon the flower--the object of its visit being, of course,

the sweets located in the five horn-shaped nectaries. In order to reach

this nectar the insect must hang to the bulky blossom. Instantly, and

almost of necessity, it would seem, one or more of the feet are seen to

enter the upper opening of the fissure, and during the insect's

movements are drawn through to the base. The foot is thus conducted

directly between the two viscid discs, which immediately cling closer

than a brother, and as the foot is finally withdrawn, the pollen is

pulled from its cell. The member now released seeks a fresh hold, and

the same result follows, the leg almost inevitably entering the fissure,

and this time drawing in the pollen directly against the sticky

stigmatic surface within. The five honey-horns have now been drained,

and as our bee leaves the flower he is plainly detained by this too

hearty "shake" or "grip" of his host, and quite commonly must exert a

slight struggle to free himself. As the foot is thus forcibly torn away,

the pollen mass is commonly scraped entirely off and retained within the

fissure, or perhaps parts at the stalk, leaving the terminal disc

clinging on the insect's leg. Occasionally, when more than one leg is

entangled, the dangling blossom is tossed and swayed for several seconds

by the vigorous pulling and buzzing, and a number of these temporary

captives upon a single milkweed-plant are always to be seen.

Not unfrequently the mechanism so well adapted exceeds its functions and

proves a veritable trap, as indicated in my specimens. I have found

three dead bees thus entrapped in a single umbel of blossoms, having

been exhausted in their struggles for escape; and a search among the

flowers at any time will show the frequency of this fatality, the

victims including gnats, flies, crane-flies, bugs, wasps, beetles, and

small butterflies. In every instance this prisoner is found dangling by

one or more legs, with the feet firmly held in the grip of the fissure.

Almost any bee which we may catch at random upon a milkweed gives

perfect evidence of his surroundings, its toes being decorated with the

tiny yellow tags, each successive flower giving and taking, exchanging

compliments, as it were, with his fellows. Ordinarily this fringe can

hardly prove more than an embarrassment; but we may frequently discern

an individual here and there which for some reason has received more

than his share of the milkweed's compliments. His legs are conspicuously

fringed with the yellow tags. He rests with a discouraged air upon a

neighboring leaf, while honey, and even wings, are seemingly forgotten

in his efforts to scrape off the cumbersome handicap.

[Illustration]

An interesting incident, apropos of our embarrassed bee, was narrated to

me by the late Alphonso Wood, the noted botanist. He had received by

mail from California a small box containing a hundred or more dead bees,

accompanied by a letter. The writer, an old bee-keeper, had experience,

and desired enlightenment and advice. The letter stated that his bees

were "dying by thousands from the attacks of a peculiar fungus." The

ground around the hive was littered with the victims in all stages of

helplessness, and the dead insects were found everywhere at greater

distances scattered around his premises. It needed only a casual glance

at the encumbered insects to see the nature of the malady. They were

laden two or three pairs deep, as it were, with the pollen masses of a

milkweed. The botanist wrote immediately to his anxious correspondent,

informing him, and suggesting as a remedy the discovery and destruction

of the mischievous plants, which must be thriving somewhere in his

neighborhood. A subsequent letter conveyed the thanks of the bee-keeper,

stating that the milkweeds--a whole field of them--had been found and

destroyed, and the trouble had immediately ceased. I am not aware that

Mr. Wood ever ascertained the particular species of milkweed in this

case. It is not probable that our Eastern species need ever seriously

threaten the apiary, though unquestionably large numbers of bees are

annually destroyed by its excessive hospitality. I have repeatedly found

honey-bees dead beneath the plants, and my cabinet shows a specimen of a

large bumblebee which had succumbed to its pollen burden, its feet, and

even the hairs upon its body, being fringed deep with the tiny

clubs--one of the many specimens which I have discovered as the "grist

in the mill" of that wise spider which usually spreads his catch-all

beneath the milkweeds.

* * * * *

Allied to the milkweed is another plant, the dogbane (_Apocynum_), which

has a similar trick of entrapping its insect friends. Its drooping,

fragrant, bell-shaped white flowers and long slender pods will help to

recall it. But its method of capture is somewhat similar to the

milkweed. The anthers are divided by a V-shaped cavity, into which the

insect's tongue is guided as it is withdrawn from the flower, and into

which it often becomes so tightly wedged as to render escape impossible.

I have found small moths dangling by the tongue, as seen in the

illustration below.

[Illustration]