Clearly, then, the difference between the theologian and the naturalist is

not fundamental, and evolution may be as profoundly and as particularly

theistic as it is increasingly probable. The taint of atheism which, in Dr.

Hodge's view, leavens the whole lump, is not inherent in the original grain

of Darwinism--in the principles posited--but has somehow been introduced in

the subsequent treatment. Possibly, when found, it may be eliminated.

Perhaps there is mutual misapprehension growing out of some ambiguity in the

use of terms. "Without any intention, purpose, or cooperation of God."-

These are sweeping and effectual words. How came they to be applied to

natural selection by a divine who professes that God ordained whatsoever

cometh to pass? In this wise: "The point to be proved is, that it is the

distinctive doctrine of Mr. Darwin that species owe their origin--1. Not to

the original intention of the divine mind; 2. Not to special acts of

creation calling new forms into existence at certain epochs; 3. Not to the

constant and everywhere operative efficiency of God guiding physical causes

in the production of intended effects; but 4. To the gradual accumulation

of unintended variations of structure and instinct securing some advantage

to their subjects." Then Dr. Hodge adduces "Darwin's own testimony," to the

purport that natural selection denotes the totality of natural causes and

their interactions, physical and physiological, reproduction, variation,

birth, struggle, extinction--in short, all that is going on in Nature; that

the variations which in this interplay are picked out for survival are not

intentionally guided; that "nothing can be more hopeless than the attempt

to explain this similarity of pattern in members of the same class by

utility or the doctrine of final causes" (which Dr. Hodge takes to be the

denial of any such thing as final causes); and that the interactions and

processes going on which constitute natural selection may suffice to

account for the present diversity of animals and plants (primordial

organisms being postulated and time enough given) with all their structures

and adaptations--that is, to account for them scientifically, as science

accounts for other things.

A good deal may be made of this, but does it sustain the indictment?

Moreover, the counts of the indictment may be demurred to. It seems to us

that only one of the three points which Darwin is said to deny is really

opposed to the fourth, which he is said to maintain, except as concerns the

perhaps ambiguous word unintended. Otherwise, the origin of species through

the gradual accumulation of variations--i.e., by the addition of a series

of small differences--is surely not incongruous with their origin through

"the original intention of the divine mind" or through "the constant and

everywhere operative efficiency of God."- One or both of these Mr. Darwin

(being, as Dr. Hodge says, a theist) must needs hold to in some form or

other; wherefore he may be presumed to hold the fourth proposition in such

wise as not really to contradict the first or the third. The proper

antithesis is with the second proposition only, and the issue comes to

this: Have the multitudinous forms of living creatures, past and present,

been produced by as many special and independent acts of creation at very

numerous epochs? Or have they originated under causes as natural as

reproduction and birth, and no more so, by the variation and change of

preceding into succeeding species?

Those who accept the latter alternative are evolutionists. And Dr. Hodge

fairly allows that their views, although clearly wrong, may be genuinely

theistic. Surely they need not become the less so by the discovery or by

the conjecture of natural operations through which this diversification and

continued adaptation of species to conditions is brought about. Now, Mr.

Darwin thinks--and by this he is distinguished. from most

evolutionists--that he can assign actual natural causes, adequate to the

production of the present out of the preceding state of the animal and

vegetable world, and so on backward--thus uniting, not indeed the beginning

but the far past with the present in one coherent system of Nature. But in

assigning actual natural causes and processes, and applying them to the

explanation of the whole case, Mr. Dar-win assumes the obligation of

maintaining their general sufficiency--a task from which the numerous

advocates and acceptors of evolution on the general concurrence of

probabilities and its usefulness as a working hypothesis (with or without

much conception of the manner how) are happily free. Having hit upon a

modus operandi which all who understand it admit will explain something,

and many that it will explain very much, it is to be expected that Mr.

Darwin will make the most of it. Doubtless he is far from pretending to

know all the causes and operations at work; he has already added some and

restricted the range of others; he probably looks for additions to their

number and new illustrations of their efficiency; but he is bound to expect

them all to fall within the category of what he calls natural selection (a

most expansible principle), or to be congruous with it--that is, that they

shall be natural causes. Also--and this is the critical point--he is bound

to maintain their sufficiency without intervention.

Here, at length, we reach the essential difference between Darwin, as we

understand him, and Dr. Hodge. The terms which Darwin sometimes uses, and

doubtless some of the ideas they represent, are not such as we should adopt

or like to defend; and we may say once for all--aside though it be from the

present issue--that, in our opinion, the adequacy of the assigned causes to

the explanation of the phenomena has not been made out. But we do not

understand him to deny "purpose, intention, or the cooperation of God" in

Nature. This would be as gratuitous as unphilosophical, not to say

unscientific. When he speaks of this or that particular or phase in the

course of events or the procession of organic forms as not intended, he

seems to mean not specially and disjunctively intended and not brought

about by intervention. Purpose in the whole, as we suppose, is not denied

but implied. And when one considers how, under whatever view of the case,

the designed and the contingent lie inextricably commingled in this world

of ours, past man's disentanglement, and into what metaphysical dilemmas

the attempt at unraveling them leads, we cannot greatly blame the

naturalist for relegating such problems to the philosopher and the

theologian. If charitable, these will place the most favorable construction

upon attempts to extend and unify the operation of known secondary causes,

this being the proper business of the naturalist and physicist; if wise,

they will be careful not to predicate or suggest the absence of intention

from what comes about by degrees through the continuous operation of

physical causes, even in the organic world, lest, in their endeavor to

retain a probable excess of supernaturalism in that realm of Nature, they

cut away the grounds for recognizing it at all in inorganic Nature, and so

fall into the same condemnation that some of them award to the Darwinian.

Moreover, it is not certain that Mr. Darwin would very much better his

case, Dr. Hodge being judge, if he did propound some theory of the nexus of

divine causation and natural laws, or even if he explicitly adopted the one

or the other of the views which he is charged with rejecting. Either way he

might meet a procrustean fate; and, although a saving amount of theism

might remain, he would not be sound or comfortable. For, if he predicates

"the constant and everywhere operative efficiency of God," he may "lapse

into the same doctrine" that the Duke of Argyll and Sir John Herschel "seem

inclined to," the latter of whom is blamed for thinking "it but reasonable

to regard the force of gravitation as the direct or indirect result of a

consciousness or will existing somewhere," and the former for regarding "it

unphilosophical 'to think or speak as if the forces of Nature were either

independent of or even separate from the Creator's power' ": while if he

falls back upon an "original intention of the divine mind," endowing matter

with forces which he foresaw and intended should produce such results as

these contrivances in Nature, he is told that this banishes God from the

world, and is inconsistent with obvious facts. And that because of its

implying that "He never interferes to guide the operation of physical

causes. We italicize the word, for interference proves to be the keynote of

Dr. Hodge's system. Interference with a divinely ordained physical Nature

for the accomplishment of natural results! An unorthodox friend has just

imparted to us, with much misgiving and solicitude lest he should be thought

irreverent, his tentative hypothesis, which is, that even the Creator may be

conceived to have improved with time and experience! Never before was this

theory so plainly and barely put before us. We were obliged to say that, in

principle and by implication, it was not wholly original.

But in such matters, which are far too high for us, no one is justly to be

held responsible for the conclusions which another may draw from his

principles or assumptions. Dr. Hodge's particular view should be gathered

from his own statement of it:

"In the external world there is always and everywhere indisputable evidence

of the activity of two kinds of force, the one physical, the other mental.

The physical belongs to matter, and is due to the properties with which it

has been endowed; the other is the everywhere present and ever-acting mind

of God. To the latter are to be referred all the manifestations of design

in Nature, and the ordering of events in Providence. This doctrine does not

ignore the efficiency of second causes; it simply asserts that God

overrules and controls them. Thus the Psalmist says: 'I am fearfully and

wonderfully made. My substance was not hid from Thee when I was made in

secret, and curiously wrought (or embroidered) in the lower parts of the

earth. . . . God makes the grass to grow, and herbs for the children of

men.'- He sends rain, frost, and snow. He controls the winds and the waves.

He determines the casting of the lot, the flight of an arrow, and the

falling of a sparrow."

Far be it from us to object to this mode of conceiving divine causation,

although, like the two other theistic conceptions referred to, it has its

difficulties, and perhaps the difficulties of both. But, if we understand

it, it draws an unusually hard and fast line between causation in organic

and inorganic Nature, seems to look for no manifestation of design in the

latter except as "God overrules and controls" second causes, and, finally,

refers to this overruling and controlling (rather than to a normal action

through endowment) all embryonic development, the growth of vegetables, and

the like. He even adds, without break or distinction, the sending of rain,

frost, and snow, the flight of an arrow, and the falling of a sparrow.

Somehow we must have misconceived the bearing of the statement; but so it

stands as one of "the three ways," and the right way, of "accounting for

contrivances in Nature; the other two being--1. Their reference to the

blind operation of natural causes; and, 2. That they were foreseen and

purposed by God, who endowed matter with forces which he foresaw and

intended should produce such results, but never interferes to guide their

operation.

In animadverting upon this latter view, Dr. Hodge brings forward an

argument against evolution, with the examination of which our remarks must

close:

"Paley, indeed, says that if the construction of a watch be an undeniable

evidence of design, it would be a still more wonderful manifestation of

skill if a watch could be made to produce other watches, and, it may be

added, not only other watches, but all kinds of timepieces, in endless

variety. So it has been asked, If a man can make a telescope, why cannot

God make a telescope which produces others like itself? This is simply

asking whether matter can be made to do the work of mind. The idea involves

a contradiction. For a telescope to make a telescope supposes it to select

copper and zinc in due proportions, and fuse them into brass; to fashion

that brass into inter-entering tubes; to collect and combine the requisite

materials for the different kinds of glass needed; to melt them, grind,

fashion, and polish them, adjust their densities, focal distances, etc.,

etc. A man who can believe that brass can do all this might as well believe

in God" (pp. 45, 46).

If Dr. Hodge's meaning is, that matter unconstructed cannot do the work of

mind, he misses the point altogether; for original construction by an

intelligent mind is given in the premises. If he means that the machine

cannot originate the power that operates it, this is conceded by all except

believers in perpetual motion, and it equally misses the point; for the

operating power is given in the case of the watch, and implied in that of

the reproductive telescope. But if he means that matter cannot be made to do

the work of mind in constructions, machines, or organisms, he is surely

wrong. "Sovitur ambulando," vel scribendo; he confuted his argument in the

act of writing the sentence. That is just what machines and organisms are

for; and a consistent Christian theist should maintain that is what all

matter is for. Finally, if, as we freely suppose, he means none of these,

he must mean (unless we are much mistaken) that organisms originated by the

Almighty Creator could not be endowed with the power of producing similar

organisms, or slightly dissimilar organisms, without successive

interventions. Then he begs the very question in dispute, and that, too, in

the face of the primal command, "Be fruitful and multiply," and its

consequences in every natural birth. If the actual facts could be ignored,

how nicely the parallel would run! "The idea involves a contradiction." For

an animal to make an animal, or a plant to make a plant, supposes it to

select carbon, hydrogen, oxygen, and nitrogen, to combine these into

cellulose and protoplasm, to join with these some phosphorus, lime, etc.,

to build them into structures and usefully-adjusted organs. A man who can

believe that plants and animals can do this (not, indeed, in the crude way

suggested, but in the appointed way) "might as well believe in God." Yes,

verily, and so he probably will, in spite of all that atheistical

philosophers have to offer, if not harassed and confused by such arguments

and statements as these.

There is a long line of gradually-increasing divergence from the

ultra-orthodox view of Dr. Hodge through those of such men as Sir William

Thomson, Herschel, Argyll, Owen, Mivart, Wallace, and Darwin, down to those

of Strauss, Vogt, and Buchner. To strike the line with telling power and

good effect, it is necessary to aim at the right place. Excellent as the

present volume is in motive and clearly as it shows that Darwinism may bear

an atheistic as well as a theistic interpretation, we fear that it will not

contribute much to the reconcilement of science and religion.

The length of the analysis of the first book on our list precludes the

notices which we intended to take of the three others. They are all the

production of men who are both scientific and religious, one of them a

celebrated divine and writer unusually versed in natural history. They all

look upon theories of evolution either as in the way of being established

or as not unlikely to prevail, and they confidently expect to lose thereby

no solid ground for theism or religion. Mr. St. Clair, a new writer, in his

"Darwinism and Design; or, Creation by Evolution," takes his ground in the

following succinct statement of his preface:

"It is being assumed by our scientific guides that the design-argument has

been driven out of the field by the doctrine of evolution. It seems to be

thought by our theological teachers that the best defense of the faith is

to deny evolution in toto, and denounce it as anti-Biblical. My volume

endeavors to show that, if evolution be true, all is not lost; but, on the

contrary, something is gained: the design-argument remains unshaken, and

the wisdom and beneficence of God receive new illustration."

Of his closing remark, that, so far as he knows, the subject has never

before been handled in the same way for the same purpose, we will only say

that the handling strikes us as mainly sensible rather than as

substantially novel. He traverses the whole ground of evolution, from that

of the solar system to "the origin of moral species." He is clearly a

theistic Darwinian without misgiving, and the arguments for that hypothesis

and for its religious aspects obtain from him their most favorable

presentation, while he combats the dysteleology of Hackel, Buchner, etc.,

not, however, with any remarkable strength.

Dr. Winchell, chancellor of the new university at Syracuse, in his volume

just issued upon the "Doctrine of Evolution," adopts it in the abstract as

"clearly as the law of universal intelligence under which complex results

are brought into existence" (whatever that may mean), accepts it

practically for the inorganic world as a geologist should, hesitates as to

the organic world, and sums up the arguments for the origin of species by

diversification unfavorably for the Darwinians, regarding it mainly from the

geological side. As some of our zoologists and palaeontologists may have

somewhat to say upon this matter, we leave it for their consideration. We

are tempted to develop a point which Dr. Winchell incidentally refers

to--viz., how very modern the idea of the independent creation and fixity

of species is, and how well the old divines got on without it. Dr. Winchell

reminds us that St. Augustine and St. Thomas Aquinas were model

evolutionists; and, where authority is deferred to, this should count for

something.

Mr. Kingsley's eloquent and suggestive "Westminster Sermons," in which he

touches here and there upon many of the topics which evolution brings up,

has incorporated into the preface a paper which he read in 187i to a

meeting of London clergy at Sion College, upon certain problems of natural

theology as affected by modern theories in science. We may hereafter have

occasion to refer to this volume. Meanwhile, perhaps we may usefully

conclude this article with two or three short extracts from it:

"The God who satisfies our conscience ought more or less to satisfy our

reason also. To teach that was Butler's mission; and he fulfilled it well.

But it is a mission which has to be refulfilled again and again, as human

thought changes, and human science develops, For if, in any age or country,

the God who seems to be revealed by Nature seems also different from the

God who is revealed by the then-popular religion, then that God and the

religion which tells of that God will gradually cease to be believed in.

"For the demands of reason--as none knew better than good Bishop

Butler--must be and ought to be satisfied. And, therefore, when a popular

war arises between the reason of any generation and its theology, then it

behooves the ministers of religion to inquire, with all humility and godly

fear, on whose side lies the fault; whether the theology which they expound

is all that it should be, or whether the reason of those who impugn it is

all that it should be."

Pronouncing it to be the duty of the naturalist to find out the how of

things, and of the natural theologian to find out the why, Mr. Kingsley

continues:

"But if it be said, 'After all, there is no why; the doctrine of evolution,

by doing away with the theory of creation, does away with that of final

causes,' let us answer boldly, 'Not in the least.' We might accept all that

Mr. Darwin, all that Prof. Huxley, all that other most able men have so

learnedly and acutely written on physical science, and yet preserve our

natural theology on the same basis as that on which Butler and Paley left

it. That we should have to develop it I do not deny.

"Let us rather look with calmness, and even with hope and good-will, on

these new theories; they surely mark a tendency toward a more, not a less,

Scriptural view of Nature.

"Of old it was said by Him, without whom nothing is made, 'My Father

worketh hitherto, and I work.' Shall we quarrel with Science if she should

show how these words are true? What, in one word, should we have to say but

this: 'We know of old that God was so wise that he could make all things;

but, behold, he is so much wiser than even that, that he can make all

things make themselves?' "

CHARLES DARWIN: A SKETCH

(Nature, June 4, 1874, accompanying a portrait)

Two British naturalists, Robert Brown and Charles Darwin, have, more than

any others, impressed their influence upon science in this nineteenth

century. Unlike as these men and their works were and are, we may most

readily subserve the present purpose in what we are called upon to say of

the latter by briefly comparing and contrasting the two.

Robert Brown died sixteen years ago, full of years and scientific honors,

and he seems to have finished, several years earlier, all the scientific

work that he had undertaken. To the other, Charles Darwin, a fair number of

productive years may yet remain, and are earnestly hoped for. Both enjoyed

the great advantage of being all their lives long free from exacting

professional duties or cares, and so were able in the main to apply

themselves to research without distraction and according to their bent.

Both, at the beginning of their career, were attached to expeditions of

exploration in the southern hemisphere, where they amassed rich stores of

observation and materials, and probably struck out, while in the field,

some of the best ideas which they subsequently developed. They worked in

different fields and upon different methods; only in a single instance, so

far as we know, have they handled the same topic; and in this the more

penetrating insight of the younger naturalist into an interesting general

problem may be appealed to in justification of a comparison which some will

deem presumptuous. Be this as it may, there will probably be little dissent

from the opinion that the characteristic trait common to the two is an

unrivaled scientific sagacity. In this these two naturalists seem to us,

each in his way, preeminent. There is a characteristic likeness,

too--underlying much difference--in their admirable manner of dealing with

facts closely, and at first hand, without the interposition of the formal

laws, vague ideal conceptions, or "glittering generalities" which some

philosophical naturalists make large use of.

A likeness may also be discerned in the way in which the work or

contributions of predecessors and contemporaries are referred to. The brief

historical summaries prefixed to many of Mr. Brown's papers are models of

judicial conscientiousness. And Mr. Darwin's evident delight at discovering

that some one else has "said his good things before him," or has been on

the verge of uttering them, seemingly equals that of making the discovery

himself. It reminds one of Goethe's insisting that his views in morphology

must have been held before him and must be somewhere on record, so obvious

did they appear to him.

Considering the quiet and retired lives led by both these men, and the

prominent place they are likely to occupy in the history of science, the

contrast between them as to contemporary and popular fame is very

remarkable. While Mr. Brown was looked up to with the greatest reverence by

all the learned botanists, he was scarcely heard of by any one else; and

out of botany he was unknown to science except as the discoverer of the

Brownian motion of minute particles, which discovery was promulgated in a

privately-printed pamphlet that few have ever seen. Although Mr. Darwin had

been for twenty years well and widely known for his "Naturalist's Journal,"

his works on "Coral Islands," on "Volcanic Islands, and especially for his

researches on the Barnacles, it was not till about fifteen years ago that

his name became popularly famous. Ever since no scientific name has been so

widely spoken. Many others have had hypotheses or systems named after them,

but no one else that we know of a department of bibliography. The nature of

his latest researches accounts for most of the difference, but not for all,

The Origin of Species is a fascinating topic, having interests and

connections with every branch of science, natural and moral. The

investigation of recondite affinities is very dry and special; its

questions, processes, and results alike--although in part generally

presentable in the shape of morphology--are mainly, like the higher

mathematics, unintelligible except to those who make them a subject of

serious study. They are especially so when presented in Mr. Brown's manner.

Perhaps no naturalist ever recorded the results of his investigations in

fewer words and with greater precision than Robert Brown: certainly no one

ever took more pains to state nothing beyond the precise point in question.

Indeed, we have sometimes fancied that he preferred to enwrap rather than to

explain his meaning; to put it into such a form that, unless you follow

Solomon's injunction and dig for the wisdom as for hid treasure, you may

hardly apprehend it until you have found it all out for yourself, when you

will have the satisfaction of perceiving that Mr. Brown not only knew all

about it, but had put it upon record. Very different from this is the way

in which Mr. Darwin takes his readers into his confidence, freely displays

to them the sources of his information, and the working of his mind, and

even shares with them all his doubts and misgivings, while in a clear

exposition he sets forth the reasons which have guided him to his

conclusions. These you may hesitate or decline to adopt, but you feel sure

that they have been presented with perfect fairness; and if you think of

arguments against them you may be confident that they have all been duly

considered before.

The sagacity which characterizes these two naturalists is seen in their

success in finding decisive instances, and their sure insight into the

meaning of things. As an instance of the latter on Mr. Darwin's part, and a

justification of our venture to compare him with the facile princeps

botanicorum, we will, in conclusion, allude to the single instance in which

they took the same subject in hand. In his papers on the organs and modes

of fecundation in Orchideae and Asclepiadeae, Mr. Brown refers more than

once to C.K. Sprengel's almost forgotten work, shows how the structure of

the flowers in these orders largely requires the agency of insects for

their fecundation, and is aware that "in Asclepiadeae . . . the insect so

readily passes from one corolla to another that it not unfrequently visits

every flower of the umbel." He must also have contemplated the transport of

pollen from plant to plant by wind and insects; and we know from another

source that he looked upon Sprengel's ideas as far from fantastic. Yet,

instead of taking the single forward step which now seems so obvious, he

even hazarded the conjecture that the insect-forms of some orchideous

flowers are intended to deter rather than to attract insects. And so the

explanation of all these and other extraordinary structures, as well as of

the arrangement of blossoms in general, and even the very meaning and need

of sexual propagation, were left to be supplied by Mr. Darwin. The aphorism

"Nature abhors a vacuum" is a characteristic specimen of the science of the

middle ages. The aphorism "Nature abhors close fertilization," and the

demonstration of the principle, belong to our age, and to Mr. Darwin. To

have originated this, and also the principle of natural selection--the

truthfulness and importance of which are evident the moment it is

apprehended--and to have applied these principles to the system of Nature in

such a manner as to make, within a dozen years, a deeper impression upon

natural history than has been made since Linnaeus, is ample title for one

man's fame.

There is no need of our giving any account or of estimating the importance

of such works as the "Origin of Species by means of Natural Selection," the

"Variation of Animals and Plants under Domestication," the "Descent of Man,

and Selection in Relation to Sex," and the "Expression of the Emotions in

Men and Animals"--a series to which we may hope other volumes may in due

time be added. We would rather, if space permitted, attempt an analysis of

the less known, but not less masterly, subsidiary essays, upon the various

arrangements for insuring cross-fertilization in flowers, for the climbing

of plants, and the like. These, as we have heard, may before long be

reprinted in a volume, and supplemented by some long-pending but still

unfinished investigations upon the action of Dionaea and Drosera--a capital

subject for Mr. Darwin's handling.

A propos to these papers, which furnish excellent illustrations of it, let

us recognize Darwin's great service to natural science in bringing back to

it Teleology; so that, instead of Morphology versus Teleology, we shall

have Morphology wedded to Teleology. To many, no doubt, evolutionary

Teleology comes in such a questionable shape as to seem shorn of all its

goodness; but they will think better of it in time, when their ideas become

adjusted, and they see what an impetus the new doctrines have given to

investigation. They are much mistaken who suppose that Darwinism is only of

speculative importance, and perhaps transient interest. In its working

applications it has proved to be a new power, eminently practical and

fruitful.

And here, again, we are bound to note a striking contrast to Mr. Brown,

greatly as we revere his memory. He did far less work than was justly to be

expected from him. Mr. Darwin not only points out the road, but labors upon

it indefatigably and unceasingly. A most commendable noblesse oblige

assures us that he will go on while strength (would we could add health)

remains. The vast amount of such work he has already accomplished might

overtax the powers of the strongest. That it could have been done at all

under constant infirm health is most wonderful.

X

INSECTIVOROUS PLANTS

(The Nation, April 2 and 9, 1874)

That animals should feed upon plants is natural and normal, and the reverse

seems impossible. But the adage, "Natura non agit saltatim," has its

application even here. It is the naturalist, rather than Nature, that draws

hard and fast lines everywhere, and marks out abrupt boundaries where she

shades off with gradations. However opposite the parts which animals and

vegetables play in the economy of the world as the two opposed kingdoms of

organic Nature, it is becoming more and more obvious that they are not only

two contiguous kingdoms, but are parts of one whole--antithetical and

complementary to each other, indeed; but such "thin partitions do the

bounds divide" that no definitions yet framed hold good without exception.

This is a world of transition in more senses than is commonly thought; and

one of the lessons which the philosophical naturalist learns, or has to

learn, is, that differences the most wide and real in the main, and the most

essential, may nevertheless be here and there connected or bridged over by

gradations. There is a limbo filled with organisms which never rise high

enough in the scale to be manifestly either animal or plant, unless it may

be said of some of them that they are each in turn and neither long. There

are undoubted animals which produce the essential material of vegetable

fabric, or build up a part of their structure of it, or elaborate the

characteristic leaf-green which, under solar light, assimilates inorganic

into organic matter, the most distinguishing function of vegetation. On the

other hand, there are plants--microscopic, indeed, but

unquestionable--which move spontaneously and freely around and among

animals that are fixed and rooted. And, to come without further parley to

the matter in hand, while the majority of animals feed directly upon plants,

"for 'tis their nature to," there are plants which turn the tables and feed

upon them. Some, being parasitic upon living animals, feed insidiously and

furtively; these, although really cases in point, are not so extraordinary,

and, as they belong to the lower orders, they are not much regarded, except

for the harm they do. There are others, and those of the highest orders,

which lure or entrap animals in ways which may well excite our special

wonder--all the more so since we are now led to conclude that they not only

capture but consume their prey.

As respects the two or three most notable instances, the conclusions which

have been reached are among the very recent acquisitions of physiological

science. Curiously enough, however, now that they are made out, it appears

that they were in good part long ago attained, recorded, and mainly

forgotten. The earlier observations and surmises shared the common fate of

discoveries made before the time, or by those who were not sagacious enough

to bring out their full meaning or importance. Vegetable morphology, dimly

apprehended by Linnaeus, initiated by Casper Frederick Wolff, and again,

independently in successive generations, by Goethe and by De Candolle,

offers a parallel instance. The botanists of Goethe's day could not see any

sense, advantage, or practical application, to be made of the proposition

that the parts of a blossom answer to leaves; and so the study of

homologies had long to wait. Until lately it appeared to be of no

consequence whatever (except, perhaps, to the insects) whether Drosera and

Sarracenia caught flies or not; and even Dionaea excited only unreflecting

wonder as a vegetable anomaly. As if there were real anomalies in Nature,

and some one plant possessed extraordinary powers denied to all others, and

(as was supposed) of no importance to itself!

That most expert of fly-catchers, Dionaea, of which so much has been

written and so little known until lately, came very near revealing its

secret to Solander and Ellis a hundred years ago, and doubtless to John

Bartram, our botanical pioneer, its C probable discoverer, who sent it to

Europe. Ellis, in his published letter to Linnaeus, with which the history

begins, described the structure and action of the living trap correctly;

noticed that the irritability which called forth the quick movement closing

the trap, entirely resided in the few small bristles of its upper face;

that this whole surface was studded C with glands, which probably secreted

a liquid; and that the trap did not open again when an insect was captured,

even upon the death of the captive, although it opened very soon when

nothing was caught, or when the irritation was caused by a bit of straw, or

any such substance. It was Linnaeus who originated the contrary and

erroneous statement, which has long prevailed in the books, that the trap

reopened when the fatigued captive became quiet, and let it go; as if the

plant caught flies in mere play and pastime! Linnaeus also omitted all

allusion to a secreted liquid--which was justifiable, as. Ellis does not

state that he had actually seen any; and, if he did see it, quite mistook

its use, supposing it to be, like the nectar of flowers, a lure for

insects, a bait for the trap. Whereas, in fact, the lure, if there be any,

must be an odor (although nothing is perceptible to the human olfactories);

for the liquid secreted by the glands never appears until the trap has

closed upon some insect, and held it at least for some hours a prisoner.

Within twenty-four or forty-eight hours this glairy liquid is abundant,

bathing and macerating the body of the perished insect. Its analogue is not

the nectar of flowers, but the saliva or the gastric juice!

The observations which compel such an inference are re-cent, and the

substance of them may be briefly stated. The late Rev. Dr. M. A. Curtis (by

whose death, two years ago, we lost one of our best botanists, and the

master in his especial line, mycology), forty years and more ago resided at

Wilmington, North Carolina, in the midst of the only district to which the

Dionaea is native; and he published, in 1834, in the first volume of the

"Journal of the Boston Society of Natural History," by far the best account

of this singular plant which had then appeared. He remarks that "the little

prisoner is not crushed and suddenly destroyed, as is sometimes supposed,"

for he had often liberated "captive flies and spiders, which sped away as

fast as fear or joy could hasten them." But he neglected to state, although

he must have noticed the fact, that the two sides of the trap, at first

concave to the contained insect, at length flatten and close down firmly

upon the prey, exerting no inconsiderable pressure, and insuring the death

of any soft-bodied insect, if it had not already succumbed to the

confinement and salivation. This last Dr. Curtis noticed, and first

discerned its import, although he hesitated to pronounce upon its

universality. That the captured insects were in some way "made subservient

to the nourishment of the plant" had been conjectured from the first. Dr.

Curtis "at times (and he might have always at the proper time) found them

enveloped in a fluid of mucilaginous consistence, which seems to act as a

solvent, the insects being more or less consumed in it." This was verified

and the digestive character of the liquid well-nigh demonstrated six or

seven years ago by Mr. Canby, of Wilmington, Delaware, who, upon a visit to

the sister-town of North Carolina, and afterward at his home, followed up

Dr. Curtis's suggestions with some capital observations and experiments.

These were published at Philadelphia in the tenth volume of Meehan's

Gardeners' Monthly, August, i868; but they do not appear to have attracted

the attention which they merited.

The points which Mr. Canby made out are, that this fluid is always poured

out around the captured insect in due time, "if the leaf is in good

condition and the prey suitable;" that it comes from the leaf itself, and

not from the decomposing insect (for, when the trap caught a plum-curculio,

the fluid was poured out while he was still alive, though very weak, and

endeavoring, ineffectively, to eat his way out); that bits of raw beef,

although sometimes rejected after a while, were generally acted upon in the

same manner--i.e., closed down upon tightly, salvered with the liquid,

dissolved mainly, and absorbed; so that, in fine, the fluid may well be

said to be analogous to the gastric juice of animals, dissolving the prey

and rendering it fit for absorption by the leaf. Many leaves remain

inactive or slowly die away after one meal; others reopen for a second and

perhaps even a third capture, and are at least capable of digesting a second

meal.

Before Mr. Canby's experiments had been made, we were aware that a similar

series had been made in England by Mr. Darwin, with the same results, and

with a small but highly-curious additional one--namely, that the fluid

secreted in the trap of Dionaea, like the gastric juice, has an acid

reaction. Having begun to mention unpublished results (too long allowed to

remain so), it may be well, under the circumstances, to refer to a still

more remarkable experiment by the same most sagacious investigator. By a

prick with a sharp lancet at a certain point, he has been able to paralyze

one-half of the leaf-trap, so that it remained motionless under the

stimulus to which the other half responded. Such high and sensitive

organization entails corresponding ailments. Mr. Canby tells us that he

gave to one of his Dionaea-subjects a fatal dyspepsia by feeding it with

cheese; and under Mr. Darwin's hands another suffers from paraplegia.

Finally, Dr. Burdon-Sanderson's experiments, detailed at the last meeting

of the British Association for the Advancement of Science, show that the

same electrical currents are developed upon the closing of the Dionaea-trap

as in the contraction of a muscle.

If the Venus's Fly-trap stood alone, it would be doubly marvelous--first,

on account of its carnivorous propensities, and then as constituting a real

anomaly in organic Nature, to which nothing leads up. Before acquiescing in

such a conclusion, the modern naturalist would scrutinize its relatives.

Now, the nearest relatives of our vegetable wonder are the sundews.

While Dionaea is as local in habitation as it is singular in structure and

habits, the Droseras or sundews are widely diffused over the world and

numerous in species. The two whose captivating habits have attracted

attention abound in bogs all around the northern hemisphere. That flies are

caught by them is a matter of common observation; but this was thought to

be purely accidental. They spread out from the root a circle of small

leaves, the upper face of which especially is beset and the margin fringed

with stout bristles (or what seem to be such, although the structure is more

complex), tipped by a secreting gland, which produces, while in vigorous

state, a globule of clear liquid like a drop of dew-- whence the name, both

Greek and English. One expects these seeming dew-drops to be dissipated by

the morning sun; but they remain unaffected. A touch shows that the

glistening drops are glutinous and extremely tenacious, as flies learn to

their cost on alighting, perhaps to sip the tempting liquid, which acts

first as a decoy and then like birdlime. A small fly is held so fast, and

in its struggles comes in contact with so many of these glutinous globules,

that it seldom escapes.

The result is much the same to the insect, whether captured in the trap of

Dionaea or stuck fast to the limed bristles of Drosera. As there are various

plants upon whose glandular hairs or glutinous surfaces small insects are

habitually caught and perish, it might be pure coincidence that the most

effectual arrangement of the kind happens to occur in the nearest relatives

of Dionaea. Roth, a keen German botanist of the eighteenth century, was the

first to detect, or at least to record, some evidence of intention in

Drosera, and to compare its action with that of Dionaea, which, through

Ellis's account, had shortly before been made known in Europe. He noticed

the telling fact that not only the bristles which the unfortunate insect

had come in contact with, but also the surrounding rows, before widely

spreading, curved inward one by one, although they had not been touched, so

as within a few hours to press their glutinous tips likewise against the

body of the captive insect--thus doubling or quadrupling the bonds of the

victim and (as we may now suspect) the surfaces through which some part of

the animal substance may be imbibed. For Roth surmised that both these

plants were, in their way, predaceous. He even observed that the disk of

the Drosera-leaf itself often became concave and enveloped the prey. These

facts, although mentioned now and then in some succeeding works, were

generally forgotten, except that of the adhesion of small insects to the

leaves of sundews, which must have been observed in every generation. Up to

and even within a few years past, if any reference was made to these

asserted movements (as by such eminent physiologists as Meyen and

Treviranus) it was to discredit them. Not because they are difficult to

verify, but because, being naturally thought improbable, it was easier to

deny or ignore them. So completely had the knowledge of almost a century

ago died out in later years that, when the subject was taken up anew in our

days by Mr. Darwin, he had, as we remember, to advertise for it, by sending

a "note and query" to the magazines, asking where any account of the

fly-catching of the leaves of sundew was recorded.

When Mr. Darwin takes a matter of this sort in hand, he is not likely to

leave it where he found it. He not only confirmed all Roth's observations

as to the incurving of the bristles toward and upon an insect entangled on

any part of the disk of the leaf, but also found that they responded

similarly to a bit of muscle or other animal substance, while to any

particles of inorganic matter they were nearly indifferent. To minute

fragments of carbonate of ammonia, however, they were more responsive. As

these remarkable results, attained (as we are able to attest) half a dozen

years ago, remained unpublished (being portions of an investigation not yet

completed), it would have been hardly proper to mention them, were it not

that independent observers were beginning to bring out the same or similar

facts. Mrs. Treat, of New Jersey, noticed the habitual infolding of the

leaf in the longer-leaved species of sundew (American Journal of Science

for November, 1871), as was then thought for the first time--Roth's and

Withering's observations not having been looked up. In recording this, the

next year, in a very little book, entitled "How Plants Behave," the

opportunity was taken to mention, in the briefest way, the capital

discovery of Mr. Darwin that the leaves of Drosera act differently when

different objects are placed upon them, the bristles closing upon a

particle of raw meat as upon a living insect, while to a particle of chalk

or wood they are nearly inactive. The same facts were independently brought

out by Mr. A. W. Bennett at the last year's meeting of the British

Association for the Advancement of Science, and have been mentioned in the

journals.

If to these statements, which we may certify, were added some far more

extraordinary ones, communicated to the French Academy of Science in May

last by M. Zeigler, a stranger story of discrimination on the part of

sundew-bristles would be told. But it is safer to wait for the report of

the committee to which these marvels were referred, and conclude this

sufficiently "strange eventful history" with some details of experiments

made last summer by Mrs. Treat, of New Jersey, and published in the December

number of the American Naturalist. It is well to note that Mrs. Treat

selects for publication the observations of one particular day in July,

when the sundew-leaves were unusually active; for their moods vary with

the weather, and also in other unaccountable ways, although in general the

sultrier days are the most appetizing:

"At fifteen minutes past ten of the same day I placed bits of raw beef on

some of the most vigorous leaves of Drosera longifolia. Ten minutes past

twelve, two of the leaves had folded around the beef, hiding it from sight.

Half-past eleven of the same day, I placed living flies on the leaves of D.

longifolia. At 12 and 48 minutes one of the leaves had folded entirely

around its victim, the other leaves had partially folded, and the flies had

ceased to struggle. By 2 and 30 minutes four leaves had each folded around

a fly. . . . I tried mineral substances--bits of dry chalk, magnesia, and

pebbles. In twenty-four hours, neither the leaves nor their bristles had

made any move like clasping these articles. I wet a piece of chalk in

water, and in less than an hour the bristles were curving about it, but

soon unfolded again, leaving the chalk free on the blade of the leaf.

Parallel experiments made on D. rotundifolia, with bits of beef and of

chalk, gave the same results as to the action of the bristles; while with a

piece of raw apple, after eleven hours, "part of the bristles were clasping

it, but not so closely as the beef," and in twenty-four hours "nearly all

the bristles were curved toward it, but not many of the glands were

touching it."

To make such observations is as easy as it is interesting. Throughout the

summer one has only to transfer plants of Drosera from the bogs into pots

or pans filled with wet moss--if need be, allowing them to become

established in the somewhat changed conditions, or even to put out fresh

leaves--and to watch their action or expedite it by placing small flies

upon the disk of the leaves. The more common round-leaved sundew acts as

well as the other by its bristles, and the leaf itself is sometimes almost

equally prehensile, although in a different way, infolding the whole border

instead of the summit only. Very curious, and even somewhat painful, is the

sight when a fly, alighting upon the central dew-tipped bristles, is held

as fast as by a spider's web; while the efforts to escape not only entangle

the insect more hopelessly as they exhaust its strength, but call into

action the surrounding bristles, which, one by one, add to the number of the

bonds, each by itself apparently feeble, but in their combination so

effectual that the fly may be likened to the sleeping Gulliver made fast in

the tiny but multitudinous toils of the Liliputians. Anybody who can

believe that such an apparatus was not intended to capture flies might say

the same of a spider's web.

Is the intention here to be thought any the less real because there are

other species of Drosera which are not so perfectly adapted for

fly-catching, owing to the form of their leaves and the partial or total

want of cooperation of their scattered bristles? One such species, D.

filiformis, the thread-leaved sundew, is not uncommon in this country, both

north and south of the district that Dionaea locally inhabits. Its leaves

are long and thread-shaped, beset throughout with glutinous gland-tipped

bristles, but wholly destitute of a blade. Flies, even large ones, and even

moths and butterflies, as Mrs. Treat and Mr. Canby affirm (in the American

Naturalist), get stuck fast to these bristles, whence they seldom escape.

Accidental as such captures are, even these thread-shaped leaves respond

more or less to the contact, somewhat in the manner of their brethren. In

Mr. Canby's recent and simple experiment, made at Mr. Darwin's suggestion,

when a small fly alights upon a leaf a little below its slender apex, or

when a bit of crushed fly is there affixed, within a few hours the tip of

the leaf bends at the point of contact, and curls over or around the body

in question; and Mrs. Treat even found that when living flies were pinned

at half an inch in distance from the leaves, these in forty minutes had

bent their tips perceptibly toward the flies, and in less than two hours

reached them! If this be confirmed--and such a statement needs ample

confirmation--then it may be suspected that these slender leaves not only

incurve after prolonged contact, just as do the leaf-stalks of many

climbers, but also make free and independent circular sweeps, in the manner

of twining stems and of many tendrils.

Correlated movements like these indicate purpose. When performed by

climbing plants, the object and the advantage are obvious. That the

apparatus and the actions of Dionaea and Drosera are purposeless and

without advantage to the plants themselves, many have been believed in

former days, when it was likewise conceived that abortive and functionless

organs were specially created "for the sake of symmetry" and to display a

plan; but this is not according to the genius of modern science.

In the cases of insecticide next to be considered, such evidence of intent

is wanting, but other and circumstantial evidence may be had, sufficient to

warrant convictions. Sarracenias have hollow leaves in the form of pitchers

or trumpet-shaped tubes, containing water, in which flies and other insects

are habitually drowned. They are all natives of the eastern side of North

America, growing in bogs or low ground, so that they cannot be supposed to

need the water as such. Indeed, they secrete a part if not all of it. The

commonest species, and the only one at the North, which ranges from

Newfoundland to Florida, has a broad-mouthed pitcher with an upright lid,

into which rain must needs fall more or less. The yellow Sarracenia, with

long tubular leaves, called "trumpets in the Southern States, has an

arching or partly upright lid, raised well above the orifice, so that some

water may rain in; but a portion is certainly secreted there, and may be

seen bedewing the sides and collected at the bottom before the mouth opens.

In other species, the orifice is so completely overarched as essentially to

prevent the access of water from without. In these tubes, mainly in the

water, flies and other insects accumulate, perish, and decompose. Flies

thrown into the open-mouthed tube of the yellow Sarracenia, even when free

from water, are unable to get out--one hardly sees why, except that they

cannot fly directly upward; and microscopic chevaux-de-frise of fine,

sharp-pointed bristles which line most of the interior, pointing strictly

downward, may be a more effectual obstacle to crawling up the sides than

one would think possible. On the inside of the lid or hood of the purple

Northern species, the bristles are much stronger; but an insect might

escape by the front without encountering these. In this species, the

pitchers, however, are so well supplied with water that the insects which

somehow are most abundantly attracted thither are effectually drowned, and

the contents all summer long are in the condition of a rich liquid manure.

That the tubes or pitchers of the Southern species are equally attractive

and fatal to flies is well known. Indeed, they are said to be taken into

houses and used as fly-traps. There is no perceptible odor to draw insects,

except what arises from the decomposition of macerated victims; nor is any

kind of lure to be detected at the mouth of the pitcher of the common

purple-flowered species. Some incredulity was therefore natural when it was

stated by a Carolinian correspondent (Mr. B.F. Grady) that in the

long-leaved, yellow-flowered species the lid just above the mouth of the

tubular pitcher habitually secretes drops of a sweet and viscid liquid,

which attracts flies and apparently intoxicates them, since those that sip

it soon become unsteady in gait and mostly fall irretrievably into the well

beneath. But upon cultivating plants of this species, obtained for the

purpose, the existence of this lure was abundantly verified; and, although

we cannot vouch for its inebriating quality, we can no longer regard it as

unlikely.

No sooner was it thus ascertained that at least one species of Sarracenia

allures flies to their ruin than it began to appear that--just as in the

case of Drosera--most of this was a mere revival of obsolete knowledge. The

"insect-destroying process" was known and well described sixty years ago,

the part played by the sweet exudation indicated, and even the intoxication

perhaps hinted at, although evidently little thought of in those

ante-temperance days. Dr. James Macbride, of South Carolina--the early

associate of Elliott in his "Botany of South Carolina and Georgia," and to

whose death, at the age of thirty-three, cutting short a life of remarkable

promise, the latter touchingly alludes in the preface to his second

volume--sent to Sir James Edward Smith an account of his observations upon

this subject, made in 1810 and the following years. This was read to the

Linnaean Society in 1815, and published in the twelfth volume of its

"Transactions." From this forgotten paper (to which attention has lately

been recalled) we cull the following extracts, premising that the

observations mostly relate to a third species, Sarracenia adunca, alias

variolaris, which is said to be the most efficient fly-catcher of the kind:

"If, in the months of May, June, or July, when the leaves of those plants

perform their extraordinary functions in the greatest perfection, some of

them be removed to a house and fixed in an erect position, it will soon be

perceived that flies are attracted by them. These insects immediately

approach the fauces of the leaves, and, leaning over their edges, appear to

sip with eagerness something from their internal surfaces. In this position

they linger; but at length, allured as it would seem by the pleasure of

taste, they enter the tubes. The fly which has thus changed its situation

will be seen to stand unsteadily; it totters for a few seconds, slips, and

falls to the bottom of the tube, where it is either drowned or attempts in

vain to ascend against the points of the hairs. The fly seldom takes wing

in its fall and escapes. . . . in a house much infested with flies, this

entrapment goes on so rapidly that a tube is filled in a few hours, and it

becomes necessary to add water, the natural quantity being insufficient to

drown the imprisoned insects. The leaves of S. adunca and rubra might well

be employed as fly-catchers; indeed, I am credibly informed they are in

some neighborhoods. The leaves of the S. flava [the species to which our

foregoing remarks mainly relate], although they are very capacious, and

often grow to the height of three feet or more, are never found to contain

so many insects as those of the species above mentioned.

"The cause which attracts flies is evidently a sweet, viscid substance

resembling honey, secreted by or exuding from the internal surface of the

tube . . . From the margin, where it commences, it does not extend lower

than one-fourth of an inch.

"The falling of the insect as soon as it enters the tube is wholly

attributable to the downward or inverted position of the hairs of the

internal surface of the leaf. At the bottom of a tube split open, the hairs

are plainly discernible pointing downward; as the eye ranges upward, they

gradually become shorter and attenuated, till at or just below the surface

covered by the bait they are no longer perceptible to the naked eye nor to

the most delicate touch. It is here that the fly cannot take a hold

sufficiently strong to support itself, but falls. The in. ability of

insects to crawl up against the points of the hairs I have often tested in

the most satisfactory manner."

From the last paragraph it may be inferred that Dr. Macbride did not

suspect any inebriating property in the nectar, and in a closing note there

is a conjecture of an impalpable loose powder in S. flava, at the place

where the fly stands so unsteadily, and from which it is supposed to slide.

We incline to take Mr. Grady's view of the case.

The complete oblivion into which this paper and the whole subject had

fallen is the more remarkable when it is seen that both are briefly but

explicitly referred to in Elliott's book, with which botanists are

familiar.

It is not so wonderful that the far earlier allusion to these facts by the

younger Bartram should have been overlooked or disregarded. With the genuine

love of Nature and fondness for exploration, 'William Bartram did not

inherit the simplicity of his father, the earliest native botanist of this

country. Fine writing was his foible; and the preface to his well-known

"Travels" (published at Philadelphia in 1791) is its full-blown

illustration, sometimes perhaps deserving the epithet which he applies to

the palms of Florida--that of pomposity. In this preface he declares that

"all the Sarracenias are insect-catchers, and so is the Drosera

rotundifolia. Whether the insects caught in their leaves, and which

dissolve and mix with the fluid, serve for aliment or support to these kind

of plants is doubtful," he thinks, but he should be credited with the

suggestion. In one sentence he speaks of the quantities of insects which,

"being invited down to sip the mellifluous exuvia from the interior surface

of the tube, where they inevitably perish," being prevented from returning

by the stiff hairs all pointing downward. This, if it refers to the sweet

secretion, would place it below, and not, as it is, above the bristly

surface, while the liquid below, charged with decomposing insects, is

declared in an earlier sentence to be "cool and animating, limpid as the

morning dew." Bartram was evidently writing from memory; and it is very

doubtful if he ever distinctly recognized the sweet exudation which entices

insects.

Why should these plants take to organic food more than others? If we cannot

answer the question, we may make a probable step toward it. For plants that

are not parasitic, these, especially the sundews, have much less than the

ordinary amount of chlorophyll--that is, of the universal leaf-green upon

which the formation of organic matter out of inorganic materials depends.

These take it instead of making it, to a certain extent.

What is the bearing of these remarkable adaptations and operations upon

doctrines of evolution? There seems here to be a field on which the

specific creationist, the evolutionist with design, and the necessary

evolutionist, may fight out an interesting, if not decisive, "triangular

duel."

XI

INSECTIVOROUS AND

CLIMBING PLANTS [XI-1]

(The Nation, January 6 and 13, 1876)

"Minerals grow; vegetables grow and live; animals grow, live, and feel;"

this is the well-worn, not to say out-worn, diagnosis of the three kingdoms

by Linnaeus. It must be said of it that the agreement indicated in the

first couplet is unreal, and that the distinction declared in the second is

evanescent. Crystals do not grow at all in the sense that plants and

animals grow. On the other hand, if a response to external impressions by

special movements is evidence of feeling, vegetables share this endowment

with animals; while, if conscious feeling is meant, this can be affirmed

only of the higher animals. What appears to remain true is, that the

difference is one of successive addition. That the increment in the organic

world is of many steps; that in the long series no absolute lines separate,

or have always separated, organisms which barely respond to impressions

from those which more actively and variously respond, and even from those

that consciously so respond--this, as we all know, is what the author of the

works before us has undertaken to demonstrate. Without reference here either

to that part of the series with which man is connected, and in some sense

or other forms a part of, or to that lower limbo where the two organic

kingdoms apparently merge--or whence, in evolutionary phrase, they have

emerged--Mr. Darwin, in the present volumes, directs our attention to the

behavior of the highest plants alone. He shows that some (and he might add

that all) of them execute movements for their own advantage, and that some

capture and digest living prey. When plants are seen to move and to devour,

what faculties are left that are distinctively animal?

As to insectivorous or otherwise carnivorous plants, we have so recently

here discussed this subject--before it attained to all this new

popularity--that a brief account of Mr. Darwin's investigation may

suffice.[XI-2] It is full of interest as a physiological research, and is a

model of its kind, as well for the simplicity and directness of the means

employed as for the clearness with which the results are brought

out--results which any one may verify now that the way to them is pointed

out, and which, surprising as they are, lose half their wonder in the ease

and sureness with which they seem to have been reached.

Rather more than half the volume is devoted to one subject, the

round-leaved sundew (Drosera rotundifolia), a rather common plant in the

northern temperate zone. That flies stick fast to its leaves, being limed

by the tenacious seeming dew-drops which stud its upper face and margins,

had long been noticed in Europe and in this country. We have heard hunters

and explorers in our Northern woods refer with satisfaction to the fate

which in this way often befalls one of their plagues, the black fly of early

summer. And it was known to some observant botanists in the last century,

although forgotten or discredited in this, that an insect caught on the

viscid glands it has happened to alight upon is soon fixed by many

more--not merely in consequence of its struggles, but by the spontaneous

incurvation of the stalks of surrounding and untouched glands; and even the

body of the leaf had been observed to incurve or become cup-shaped so as

partly to involve the captive insect.

Mr. Darwin's peculiar investigations not only confirm all this, but add

greater wonders. They relate to the sensitiveness of these tentacles, as he

prefers to call them, and the mode in which it is manifested; their power

of absorption; their astonishing discernment of the presence of animal or

other soluble azotized matter, even in quantities so minute as to rival the

spectroscope--that most exquisite instrument of modern research--in

delicacy; and, finally, they establish the fact of a true digestion, in all

essential respects similar to that of the stomach of animals.

First as to sensitiveness and movement. Sensitiveness is manifested by

movement or change of form in response to an external impression. The

sensitiveness in the sundew is all in the gland which surmounts the

tentacle. To incite movement or other action, it is necessary that the

gland itself should be reached. Anything laid on the surface of the viscid

drop, the spherule of clear, glairy liquid which it secretes, produces no

effect unless it sinks through to the gland; or unless the substance is

soluble and reaches it in solution, which, in the case of certain

substances, has the same effect. But the glands themselves do not move, nor

does any neighboring portion of the tentacle. The outer and longer

tentacles bend inward (toward the centre of the leaf) promptly, when the

gland is irritated or stimulated, sweeping through an arc of 1800 or less,

or more--the quickness and the extent of the inflection depending, in

equally vigorous leaves, upon the amount of irritation or stimulation, and

also upon its kind. A tentacle with a particle of raw meat on its gland

sometimes visibly begins to bend in ten seconds, becomes strongly incurved

in five minutes, and its tip reaches the centre of the leaf in half an

hour; but this is a case of extreme rapidity. A particle of cinder, chalk,

or sand, will also incite the bending, if actually brought in contact with

the gland, not merely resting on the drop; but the inflection is then much

less pronounced and more transient. Even a bit of thin human hair, only

1/8000 of an inch in length, weighing only the 1/78740 of a grain, and

largely supported by the viscid secretion, suffices to induce movement;

but, on the other hand, one or two momentary, although rude, touches with a

hard object produce no effect, although a repeated touch or the slightest

pressure, such as that of a gnat's foot, prolonged for a short time, causes

bending. The seat of the movement is wholly or nearly confined to a portion

of the lower part of the tentacle, above the base, where local irritation

produces not the slightest effect. The movement takes place only in

response to some impression made upon its own gland at the distant

extremity, or upon other glands far more remote. For if one of these members

suffers irritation the others sympathize with it. Very noteworthy is the

correlation between the central tentacles, upon which an insect is most

likely to alight, and these external and larger ones, which, in proportion

to their distance from the centre, take the larger share in the movement.

The shorter central ones do not move at all when a bit of meat, or a

crushed fly, or a particle of a salt of ammonia, or the like, is placed upon

them; but they transmit their excitation across the leaf to the surrounding

tentacles on all sides; and they, although absolutely untouched, as they

successively receive the mysterious impulse, bend strongly inward, just as

they do when their own glands are excited. Whenever a tentacle bends in

obedience to an impulse from its own gland, the movement is always toward

the centre of the leaf; and this also takes place, as we have seen, when an

exciting object is lodged at the centre. But when the object is placed upon

either half of the leaf, the impulse radiating thence causes all the

surrounding untouched tentacles to bend with precision toward the point of

excitement, even the central tentacles, which are motionless when

themselves charged, now responding to the call. The inflection which

follows mechanical irritation or the presence of any inorganic or insoluble

body is transient; that which follows the application of organic matter

lasts longer, more or less, according to its nature and the amount; but

sooner or later the tentacles resume their former position, their glands

glisten anew with fresh secretion, and they are ready to act again.

As to how the impulse is originated and propagated, and how the movements

are made, comparatively simple as the structure is, we know as little as we

do of the nature of nervous impulse and muscular motion. But two things Mr.

Darwin has wellnigh made out, both of them by means and observations so

simple and direct as to command our confidence, although they are contrary

to the prevalent teaching. First, the transmission is through the ordinary

cellular tissue, and not through what are called the fibrous or vascular

bundles. Second, the movement is a vital one, and is effected by contraction

on the side toward which the bending takes place, rather than by turgescent

tension of the opposite side. The tentacle is pulled over rather than

pushed over. So far all accords with muscular action.

The operation of this fly-catching apparatus, in any case, is plain. If the

insect alights upon the disk of the leaf, the viscid secretion holds it

fast--at least, an ordinary fly is unable to escape--its struggles only

increase the number of glands involved and the amount of excitement; this

is telegraphed to the surrounding and successively longer tentacles, which

bent over in succession, so that within ten to thirty hours, if the leaf is

active and the fly large enough, every one of the glands (on the average,

nearly two hundred in number) will be found applied to the body of the

insect. If the insect is small, and the lodgment toward one side, only the

neighboring tentacles may take part in the capture. If two or three of the

strong marginal tentacles are first encountered, their prompt inflection

carries the intruder to the centre, and presses it down upon the glands

which thickly pave the floor; these notify all the surrounding tentacles of

the capture, that they may share the spoil, and the fate of that victim is

even as of the first. A bit of meat or a crushed insect is treated in the

same way.

This language implies that the animal matter is in some way or other

discerned by the tentacles, and is appropriated. Formerly there was only a

presumption of this, on the general ground that such an organization could

hardly be purposeless. Yet, while such expressions were natural, if not

unavoidable, they generally were used by those familiar with the facts in a

half-serious, half-metaphorical sense. Thanks to Mr. Darwin's

investigations, they may now be used in simplicity and seriousness.

That the glands secrete the glairy liquid of the drop is evident, not only

from its nature, but from its persistence through a whole day's exposure to

a summer sun, as also from its renewal after it has been removed, dried up,

or absorbed. That they absorb as well as secrete, and that the whole

tentacle may be profoundly affected thereby, are proved by the different

effects, in kind and degree, which follow the application of different

substances. Drops of rain-water, like single momentary touches of a solid

body, produce no effect, as indeed they could be of no advantage; but a

little carbonate of ammonia in the water, or an infusion of meat, not only

causes inflection, but promptly manifests its action upon the contents of

the cells of which the tentacle is constructed. These cells are

sufficiently transparent to be viewed under the microscope without

dissection or other interference; and the change which takes place in the

fluid contents of these cells, when the gland above has been acted upon, is

often visible through a weak lens, or sometimes even by the naked eye,

although higher powers are required to discern what actually takes place.

This change, which Mr. Darwin discovered, and turns to much account in his

researches, he terms "aggregation of the protoplasm." When untouched and

quiescent, the contents appear as an homogeneous purple fluid. When the

gland is acted upon, minute purple particles appear, suspended in the now

colorless or almost colorless fluid; and this change appears first in the

cells next the gland, and then in those next beneath, traveling down the

whole length of the tentacle. When the action is slight, this appearance

does not last long; the particles of "aggregated protoplasm redissolved, the

process of redissolution traveling upward from the base of the tentacle to

the gland in a reverse direction to that of the aggregation. Whenever the

action is more prolonged or intense, as when a bit of meat or crushed fly,

or a fitting solution, is left upon the gland, the aggregation proceeds

further, so that the whole protoplasm of each cell condenses into one or

two masses, or into a single mass which will often separate into two, which

afterward reunite; indeed, they incessantly change their forms and

positions, being never at rest, although their movements are rather slow.

In appearance and movements they are very like amoebae and the white

corpuscles of the blood. Their motion, along with the streaming movement of

rotation in the layer of white granular protoplasm that flows along the

walls of the cell, under the high powers of the microscope "presents a

wonderful scene of vital activity." This continues while the tentacle is

inflected or the gland fed by animal matter, but vanishes by dissolution

when the work is over and the tentacle straightens. That absorption takes

place, and matter is conveyed from cell to cell, is well made out,

especially by the experiments with carbonate of ammonia. Nevertheless, this

aggregation is not dependent upon absorption, for it equally occurs from

mechanical irritation of the gland, and always accompanies inflection,

however caused, though it may take place without it. This is also apparent

from the astonishingly minute quantity of certain substances which suffices

to produce sensible inflection and aggregation--such, for instance, as the

1/20000000 or even the 1/30000000 of a grain of phosphate or nitrate of

ammonia!

By varied experiments it was found that the nitrate of ammonia was more

powerful than the carbonate, and the phosphate more powerful than the

nitrate, this result being intelligible from the difference in the amount

of nitrogen in the first two salts, and from the presence of phosphorus in

the third. There is nothing surprising in the absorption of such extremely

dilute solutions by a gland. As our author remarks: "All physiologists

admit that the roots of plants absorb the salts of ammonia brought to them

by the rain; and fourteen gallons of rain-water contain a grain of ammonia;

therefore, only a little more than twice as much as in the weakest solution

employed by me. The fact which appears truly wonderful is that the

1/20000000 of a grain of the phosphate of ammonia, including less than

1/30000000 of efficient matter (if the water of crystallization is

deducted), when absorbed by a gland, should induce some change in it which

leads to a motor impulse being transmitted down the whole length of the

tentacle, causing its basal part to bend, often through an angle of 180

degrees." But odoriferous particles which act upon the nerves of animals

must be infinitely smaller, and by these a dog a quarter of a mile to the

leeward of a deer perceives his presence by some change in the olfactory

nerves transmitted through them to the brain.

When Mr. Darwin obtained these results, fourteen years ago, he could claim

for Drosera a power and delicacy in the detection of minute quantities of a

substance far beyond the resources of the most skillful chemist; but in a

foot-note he admits that "now the spectroscope has altogether beaten

Drosera; for, according to Bunsen and Kirchhoff, probably less than the

1/200000000 of a grain of sodium can be thus detected."

Finally, that this highly-sensitive and active living organism absorbs,

will not be doubted when it is proved to digest, that is, to dissolve

otherwise insoluble animal matter by the aid of special secretions. That it

does this is now past doubting. In the first place, when the glands are

excited they pour forth an increased amount of the ropy secretion. This

occurs directly when a bit of meat is laid upon the central glands; and the

influence which they transmit to the long-stalked marginal glands causes

them, while incurving their tentacles, to secrete more copiously long

before they have themselves touched anything. The primary fluid, secreted

without excitation, does not of itself digest. But the secretion under

excitement changes in Nature and becomes acid. So, according to Schiff,

mechanical irritation excites the glands of the stomach to secrete an acid.

In both this acid appears to be necessary to, but of itself insufficient

for, digestion. The requisite solvent, a kind of ferment called pepsin,

which acts only in the presence of the acid, is poured forth by the glands

of the stomach only after they have absorbed certain soluble nutritive

substances of the food; then this pepsin promptly dissolves muscle,

fibrine, coagulated albumen, cartilage, and the like. Similarly it appears

that Drosera-glands, after irritation by particles of glass, did not act

upon little cubes of albumen. But when moistened with saliva, or replaced

by bits of roast-meat or gelatine, or even cartilage, which supply some

soluble peptone-matter to initiate the process, these substances are

promptly acted upon, and dissolved or digested; whence it is inferred that

the analogy with the stomach holds good throughout, and that a ferment

similar to pepsin is poured out under the stimulus of some soluble animal

matter. But the direct evidence of this is furnished only by the related

carnivorous plant, Dionaea, from which the secretions, poured out when

digestion is about to begin, may be collected in quantity sufficient for

chemical examination. In short, the experiments show "that there is a

remarkable accordance in the power of digestion between the gastric juice

of animals, with its pepsin and hydrochloric acid, and the secretion of

Drosera, with its ferment and acid belonging to the acetic series. We can,

therefore, hardly doubt that the ferment in both cases is closely similar,

if not identically the same. That a plant and an animal should pour forth

the same, or nearly the same, complex secretion, adapted for the same

purpose of digestion, is a new and wonderful fact in physiology."

There are one or two other species of sundew--one of them almost as common

in Europe and North America as the ordinary round-leaved species--which act

in the same way, except that, having their leaves longer in proportion to

their breadth, their sides never curl inward, but they are much disposed to

aid the action of their tentacles by incurving the tip of the leaf, as if

to grasp the morsel. There are many others, with variously less efficient

and less advantageously arranged insectivorous apparatus, which, in the

language of the new science, may be either on the way to acquire something

better, or of losing what they may have had, while now adapting themselves

to a proper vegetable life. There is one member of the family (Drosophyllum

Lusitanicum), an almost shrubby plant, which grows on dry and sunny hills

in Portugal and Morocco--which the villagers call "the flycatcher," and

hang up in their cottages for the purpose--the glandular tentacles of which

have wholly lost their powers of movement, if they ever had any, but which

still secrete, digest, and absorb, being roused to great activity by the

contact of any animal matter. A friend of ours once remarked that it was

fearful to contemplate the amount of soul that could be called forth in a

dog by the sight of a piece of meat. Equally wonderful is the avidity for

animal food manifested by these vegetable tentacles, that can "only stand

and wait" for it.

Only a brief chapter is devoted to Dionaea of North Carolina, the Venus's

fly-trap, albeit, "from the rapidity and force of its movements, one of the

most wonderful in the world." It is of the same family as the sundew; but

the action is transferred from tentacles on the leaf to the body of the

leaf itself, which is transformed into a spring-trap, closing with a sudden

movement over the alighted insect. No secretion is provided beforehand

either for allurement or detention; but after the captive is secured,

microscopic glands within the surface of the leaf pour out an abundant

gastric juice to digest it. Mrs. Glass's classical directions in the

cook-book, "first catch your hare," are implicitly followed.

Avoiding here all repetition or recapitulation of our former narrative,

suffice it now to mention two interesting recent additions to our

knowledge, for which we are indebted to Mr. Darwin. One is a research, the

other an inspiration. It is mainly his investigations which have shown that

the glairy liquid, which is poured upon and macerates the captured insect,

accomplishes a true digestion; that, like the gastric juice of animals, it

contains both a free acid and pepsin or its analogue, these two together

dissolving albumen, meat, and the like. The other point relates to the

significance of a peculiarity in the process of capture. When the trap

suddenly incloses an insect which has betrayed its presence by touching one

of the internal sensitive bristles, the closure is at first incomplete. For

the sides approach in an arching way, surrounding a considerable cavity,

and the marginal spine-like bristles merely intercross their tips, leaving

intervening spaces through which one may look into the cavity beneath. A

good idea may be had of it by bringing the two palms near together to

represent the sides of the trap, and loosely interlocking the fingers to

represent the marginal bristles or bars. After remaining some time in this

position the closure is made complete by the margins coming into full

contact, and the sides finally flattening down so as to press firmly upon

the insect within; the secretion excited by contact is now poured out, and

digestion begins. Why these two stages? Why should time be lost by this

preliminary and incomplete closing? The query probably was never distinctly

raised before, no one noticing anything here that needed explanation.

Darwinian teleology, however, raises questions like this, and Mr. Darwin

not only propounded the riddle but solved it. The object of the partial

closing is to permit small insects to escape through the meshes, detaining

only those plump enough to be worth the trouble of digesting. For naturally

only one insect is caught at a time, and digestion is a slow business with

Dionaeas, as with anacondas, requiring ordinarily a fortnight. It is not

worth while to undertake it with a gnat when larger game may be had. To

test this happy conjecture, Mr. Canby was asked, on visiting the Dionaeas

in their native habitat, to collect early in the season a good series of

leaves in the act of digesting naturally-caught insects. Upon opening them

it was found that ten out of fourteen were engaged upon relatively large

prey, and of the remaining four three had insects as large as ants, and one

a rather small fly.

"There be land-rats and water-rats" in this carnivorous sun-dew family.

Aldrovanda, of the warmer parts of Europe and of India, is an aquatic plant,

with bladdery leaves, which were supposed to be useful in rendering the

herbage buoyant in water. But it has recently been found that the bladder

is composed of two lobes, like the trap of its relative Dionaea, or the

valves of a mussel-shell; that these open when the plant is in an active

state, are provided with some sensitive bristles within, and when these are

touched close with a quick movement. These water-traps are manifestly

adapted for catching living creatures; and the few incomplete

investigations that have already been made render it highly probably that

they appropriate their prey for nourishment; whether by digestion or by

mere absorption of decomposing animal matter, is uncertain. It is certainly

most remarkable that this family of plants, wherever met with, and under the

most diverse conditions and modes of life, should always in some way or

other be predaceous and carnivorous.

If it be not only surprising but somewhat confounding to our

classifications that a whole group of plants should subsist partly by

digesting animal matter and partly in the normal way of decomposing

carbonic acid and producing the basis of animal matter, we have, as Mr.

Darwin remarks, a counterpart anomaly in the animal kingdom. While some

plants have stomachs, some animals have roots. "The rhizocephalous

crustaceans do not feed like other animals by their mouths, for they are

destitute of an alimentary canal, but they live by absorbing through

root-like processes the juices of the animals on which they are parasitic."

To a naturalist of our day, imbued with those ideas of the solidarity of

organic Nature which such facts as those we have been considering suggest,

the greatest anomaly of all would be that they are really anomalous or

unique. Reasonably supposing, therefore, that the sundew did not stand

alone, Mr. Darwin turned his attention to other groups of plants; and,

first, to the bladderworts, which have no near kinship with the sundews,

but, like the aquatic representative of that family, are provided with

bladdery sacs, under water. In the common species of Utricularia or

bladderwort, these little sacs, hanging from submerged leaves or branches,

have their orifice closed by a lid which opens inwardly--a veritable

trapdoor. It had been noticed in England and France that they contained

minute crustacean animals. Early in the summer of 1874, Mr. Darwin

ascertained the mechanism for their capture and the great success with

which it is used. But before his account was written out, Prof. Cohn

published an excellent paper on the subject in Germany; and Mrs. Treat, of

Vineland, New Jersey, a still earlier one in this country--in the New York

Tribune in the autumn of 1874. Of the latter, Mr. Darwin remarks that she

"has been more successful than any other observer in witnessing the actual

entrance of these minute creatures." They never come out, but soon perish

in their prison, which receives a continued succession of victims, but

little, if any, fresh air to the contained water. The action of the trap is

purely mechanical, without evident irritability in the opening or shutting.

There is no evidence nor much likelihood of proper digestion; indeed, Mr.

Darwin found evidence to the contrary. But the more or less decomposed and

dissolved animal matter is doubtless absorbed into the plant; for the whole

interior of the sac is lined with peculiar, elongated and four-armed very

thin-walled processes, which contain active protoplasm, and which were

proved by experiment to "have the power of absorbing matter from weak

solutions of certain salts of ammonia and urea, and from a putrid infusion

of raw meat."

Although the bladderworts "prey on garbage," their terrestrial relatives

"live cleanly," as nobler plants should do, and have a good and true

digestion. Pinguicula, or butterwort, is the representative of this family

upon land. It gets both its Latin and its English name from the fatty or

greasy appearance of the upper face of its broad leaves; and this

appearance is due to a dense coat or pile of short-stalked glands, which

secrete a colorless and extremely viscid liquid. By this small flies, or

whatever may alight or fall upon the leaf, are held fast. These waifs might

be useless or even injurious to the plant. Probably Mr. Darwin was the

first to ask whether they might be of advantage. He certainly was the first

to show that they probably are so. The evidence from experiment, shortly

summed up, is, that insects alive or dead, and also other nitrogenous

bodies, excite these glands to increased secretion; the secretion then

becomes acid, and acquires the power of dissolving solid animal

substances--that is, the power of digestion in the manner of Drosera and

Dionaea. And the stalks of their glands under the microscope give the same

ocular evidence of absorption. The leaves of the butterwort are apt to have

their margins folded inward, like a rim or hem. Taking young and vigorous

leaves to which hardly anything had yet adhered, and of which the margins

were still flat, Mr. Darwin set within one margin a row of small flies.

Fifteen hours afterward this edge was neatly turned inward, partly covering

the row of flies, and the surrounding glands were secreting copiously. The

other edge remained flat and unaltered. Then he stuck a fly to the middle

of the leaf just below its tip, and soon both margins infolded, so as to

clasp the object. Many other and varied experiments yielded similar

results. Even pollen, which would not rarely be lodged upon these leaves, as

it falls from surrounding wind-fertilized plants, also small seeds, excited

the same action, and showed signs of being acted upon. "We may therefore

conclude," with Mr. Darwin, "that Pinguicula vulgaris, with its small

roots, is not only supported to a large extent by the extraordinary number

of insects which it habitually captures, but likewise draws some

nourishment from the pollen, leaves, and seeds, of other plants which often

adhere to its leaves. It is, therefore, partly a vegetable as well as an

animal feeder."

What is now to be thought of the ordinary glandular hairs which render the

surface of many and the most various plants extremely viscid? Their number

is legion. The Chinese primrose of common garden and house culture is no

extraordinary instance; but Mr. Francis Darwin, counting those on a small

space measured by the micrometer, estimated them at 65,371 to the square

inch of foliage, taking in both surfaces of the leaf, or two or three

millions on a moderate-sized specimen of this small herb. Glands of this

sort were loosely regarded as organs for excretion, without much

consideration of the question whether, in vegetable life, there could be

any need to excrete, or any advantage gained by throwing off such products;

and, while the popular name of catch-fly, given to several common species

of Silene, indicates long familiarity with the fact, probably no one ever

imagined that the swarms of small insects which perish upon these sticky

surfaces were ever turned to account by the plant. In many such cases, no

doubt they perish as uselessly as when attracted into the flame of a

candle. In the tobacco-plant, for instance, Mr. Darwin could find no

evidence that the glandular hairs absorb animal matter. But Darwinian

philosophy expects all gradations between casualty and complete adaptation.

It is most probable that any thin-walled vegetable structure which secretes

may also be capable of absorbing under favorable conditions. The myriads of

exquisitely-constructed glands of the Chinese primrose are not likely to be

functionless. Mr. Darwin ascertained by direct experiment that they

promptly absorb carbonate of ammonia, both in watery solution and in vapor.

So, since rain-water usually contains a small percentage of ammonia, a use

for these glands becomes apparent--one completely congruous with that of

absorbing any animal matter, or products of its decomposition, which may

come in their way through the occasional entanglement of insects in their

viscid secretion. In several saxifrages--not very distant relatives of

Drosera--the viscid glands equally manifested the power of absorption.

To trace a gradation between a simply absorbing hair with a glutinous tip,

through which the plant may perchance derive slight contingent advantage,

and the tentacles of a sundew, with their exquisite and associated

adaptations, does not much lessen the wonder nor explain the phenomena.

After all, as Mr. Darwin modestly concludes, "we see how little has been

made out in comparison with what remains unexplained and unknown." But all

this must be allowed to be an important contribution to the doctrine of the

gradual acquirement of uses and functions, and hardly to find conceivable

explanation upon any other hypothesis.

There remains one more mode in which plants of the higher grade are known

to prey upon animals; namely, by means of pitchers, urns, or tubes, in

which insects and the like are drowned or confined, and either macerated or

digested. To this Mr. Darwin barely alludes on the last page of the present

volume. The main facts known respecting the American pitcher-plants have,

as was natural, been ascertained in this country; and we gave an abstract,

two years ago, of our then incipient knowledge. Much has been learned

since, although all the observations have been of a desultory character. If

space permitted, an instructive narrative might be drawn up, as well of the

economy of the Sarracenias as of how we came to know what we do of it. But

the very little we have room for will be strictly supplementary to our

former article.

The pitchers of our familiar Northern Sarracenia, which is likewise

Southern, are open-mouthed; and, although they certainly secrete some

liquid when young, must derive most of the water they ordinarily contain

from rain. How insects are attracted is unknown, but the water abounds with

their drowned bodies and decomposing remains.

In the more southern S. flava, the long and trumpet-shaped pitchers

evidently depend upon the liquid which they themselves secrete, although at

maturity, when the hood becomes erect, rain may somewhat add to it. This

species, as we know, allures insects by a peculiar sweet exudation within

the orifice; they fall in and perish, though seldom by drowning, yet few

are able to escape; and their decomposing remains accumulate in the narrow

bottom of the vessel. Two other long-tubed species of the Southern States

are similar in these respects. There is another, S. psittacina, the

parrot-headed species, remarkable for the cowl-shaped hood so completely

inflexed over the mouth of the small pitcher that no rain can possibly

enter. Little is known, however, of the efficiency of this species as a

fly-catcher; but its conformation has a morphological interest, leading up,

as it does, to the Californian type of pitcher presently to be mentioned.

But the remaining species, S. variolaris, is the most wonderful of our

pitcher-plants in its adaptations for the capture of insects. The inflated

and mottled lid or hood overarches the ample orifice of the tubular pitcher

sufficiently to ward off the rain, but not to obstruct the free access of

flying insects. Flies, ants, and most insects, glide and fall from the

treacherous smooth throat into the deep well below, and never escape. They

are allured by a sweet secretion just within the orifice-- which was

discovered and described long ago, and the knowledge of it wellnigh

forgotten until recently. And, finally, Dr. Mellichamp, of South Carolina,

two years ago made the capital discovery that, during the height of the

season, this lure extends from the orifice down nearly to the ground, a

length of a foot or two, in the form of a honeyed line or narrow trail on

the edge of the wing-like border which is conspicuous in all these species,

although only in this one, so far as known, turned to such account. Here,

one would say, is a special adaptation to ants and such terrestrial and

creeping insects. Well, long before this sweet trail was known, it was

remarked by the late Prof. Wyman and others that the pitchers of this

species, in the savannahs of Georgia and Florida, contain far more ants

than they do of all other insects put together.

Finally, all this is essentially repeated in the peculiar Californian

pitcher-plant (Darlingtonia), a genus of the same natural family, which

captures insects in great variety, enticing them by a sweetish secretion

over the whole inside of the inflated hood and that of a curious forked

appendage, resembling a fish-tail, which overhangs the orifice. This

orifice is so concealed that it can be seen and approached only from below,

as if--the casual observer might infer--to escape visitation. But dead

insects of all kinds, and their decomposing remains, crowd the cavity and

saturate the liquid therein contained, enticed, it is said, by a peculiar

odor, as well as by the sweet lure which is at some stages so abundant as

to drip from the tips of the overhanging appendage. The principal

observations upon this pitcher-plant in its native habitat have been made

by Mrs. Austin, and only some of the earlier ones have thus far been

published by Mr. Canby. But we are assured that in this, as in the

Sarracenia variolaris, the sweet exudation extends at the proper season

from the orifice down the wing nearly to the ground, and that ants follow

this honeyed pathway to their destruction. Also, that the watery liquid in

the pitcher, which must be wholly a secretion, is much increased in

quantity after the capture of insects.

It cannot now well be doubted that the animal matter is utilized by the

plant in all these cases, although most probably only after maceration or

decomposition. In some of them even digestion, or at least the absorption

of undecomposed soluble animal juices, may be suspected; but there is no

proof of it. But, if pitchers of the Sarracenia family are only macerating

vessels, those of Nepenthes--the pitchers of the Indian Archipelago,

familiar in conservatories--seem to be stomachs. The investigations of the

President of the Royal Society, Dr. Hooker, although incomplete, wellnigh

demonstrate that these not only allure insects by a sweet secretion at the

rim and upon the lid of the cup, but also that their capture, or the

presence of other partly soluble animal matter, produces an increase and an

acidulation of the contained watery liquid, which thereupon becomes capable

of acting in the manner of that of Drosera and Dionaea, dissolving flesh,

albumen, and the like.

After all, there never was just ground for denying to vegetables the use of

animal food. The fungi are by far the most numerous family of plants, and

they all live upon organic matter, some upon dead and decomposing, some

upon living, some upon both; and the number of those that feed upon living

animals is large. Whether these carnivorous propensities of higher plants

which so excite our wonder be regarded as survivals of ancestral habits, or

as comparatively late acquirements, or even as special endowments, in any

case what we have now learned of them goes to strengthen the conclusion that

the whole organic world is akin.

The volume upon "The Movements and Habits of Climbing Plants" is a revised

and enlarged edition of a memoir communicated to the Linnaean Society in

1865, and published in the ninth volume of its Journal. There was an extra

impression, but, beyond the circle of naturalists, it can hardly have been

much known at first-hand. Even now, when it is made a part of the general

Darwinian literature, it is unlikely to be as widely read as the companion

volume which we have been reviewing; although it is really a more readable

book, and well worthy of far more extended notice at our hands than it can

now receive. The reason is obvious. It seems as natural that plants should

climb as it does unnatural that any should take animal food. Most people,

knowing that some plants "twine with the sun," and others "against the

sun," have an idea that the sun in some way causes the twining; indeed, the

notion is still fixed in the popular mind that the same species twines in

opposite directions north and south of the equator.

Readers of this fascinating treatise will learn, first of all, that the sun

has no influence over such movements directly, and that its indirect

influence is commonly adverse or disturbing, except the heat, which

quickens vegetable as it does animal life. Also, that climbing is

accomplished by powers and actions as unlike those generally predicated of

the vegetable kingdom as any which have been brought to view in the

preceding volume. Climbing plants "feel" as well as "grow and live;" and

they also manifest an automatism which is perhaps more wonderful than a

response by visible movement to an external irritation. Nor do plants grow

up their supports, as is unthinkingly supposed; for, although only growing

or newly-grown parts act in climbing, the climbing and the growth are

entirely distinct. To this there is one exception--an instructive one, as

showing how one action passes into another, and how the same result may be

brought about in different ways--that of stems which climb by rootlets, such

as of ivy and trumpet-creeper. Here the stem ascends by growth alone,

taking upward direction, and is fixed by root-lets as it grows. There is no

better way of climbing walls, precipices, and large tree-trunks.

But small stems and similar supports are best ascended by twining; and this

calls out powers of another and higher order. The twining stem does not

grow around its support, but winds around it, and it does this by a

movement the nature of which is best observed in stems which have not yet

reached their support, or have overtopped it and stretched out beyond it.

Then it may be seen that the extending summit, reaching farther and farther

as it grows, is making free circular sweeps, by night as well as by day, and

irrespective of external circumstances, except that warmth accelerates the

movement, and that the general tendency of young stems to bend toward the

light may, in case of lateral illumination, accelerate one-half the circuit

while it equally retards the other. The arrest of the revolution where the

supporting body is struck, while the portion beyond continues its movement,

brings about the twining. As to the proximate cause of this sweeping

motion, a few simple experiments prove that it results from the bowing or

bending of the free summit of the stem into a more or less horizontal

position (this bending being successively to every point of the compass,

through an action which circulates around the stem in the direction of the

sweep), and of the consequent twining, i.e., "with the sun," or with the

movement of the hands of a watch, in the hop, or in the opposite direction

in pole-beans and most twiners. Twining plants, therefore, ascend trees or

other stems by an action and a movement of their own, from which they derive

advantage. To plants liable to be overshadowed by more robust companions,

climbing is an economical method of obtaining a freer exposure to light and

air with the smallest possible expenditure of material. But twiners have

one disadvantage: to rise ten feet they must produce fifteen feet of stem

or thereabouts, according to the diameter of the support, and the openness

or closeness of the coil. A rootlet-climber saves much in this respect, but

has a restricted range of action, and other disadvantages.

There are two other modes, which combine the utmost economy of material

with freer range of action. There are, in the first place, leaf-climbers of

various sorts, agreeing only in this, that the duty of laying hold is

transferred to the leaves, so that the stem may rise in a direct line.

Sometimes the blade or leaflets, or some of them, but more commonly their

slender stalks, undertake the work, and the plant rises as a boy ascends a

tree, grasping first with one hand or arm, then with the other. Indeed, the

comparison, like the leaf-stalk, holds better than would be supposed; for

the grasping of the latter is not the result of a blind groping in all

directions by a continuous movement, but of a definite sensitiveness which

acts only upon the occasion. Most leaves make no regular sweeps; but when

the stalks of a leaf-climbing species come into prolonged contact with any

fitting extraneous body, they slowly incurve and make a turn around it, and

then commonly thicken and harden until they attain a strength which may

equal that of the stem itself. Here we have the faculty of movement to a

definite end, upon external irritation, of the same nature with that

displayed by Dionaea and Drosera, although slower for the most part than

even in the latter. But the movement of the hour-hand of the clock is not

different in nature or cause from that of the second-hand.

Finally--distribution of office being, on the whole, most advantageous and

economical, and this, in the vegetable kingdom, being led up to by

degrees--we reach, through numerous gradations, the highest style of

climbing plants in the tendril-climber. A tendril morphologically, is

either a leaf or branch of stem, or a portion of one, specially organized

for climbing. Some tendrils simply turn away from light, as do those of

grape-vines, thus taking the direction in which some supporting object is

likely to be encountered; most are indifferent to light; and many revolve

in the manner of the summit of twining stems. As the stems which bear these

highly-endowed tendrils in many cases themselves also revolve more or less,

though they seldom twine, their reach is the more extensive; and to this

endowment of automatic movement most tendrils add the other faculty, that

of incurving and coiling upon prolonged touch, or even brief contact, in

the highest degree. Some long tendrils, when in their best condition,

revolve so rapidly that the sweeping movement may be plainly seen; indeed,

we have seen a quarter-circuit in a Passiflora sicyoides accomplished in

less than a minute, and the half-circuit in ten minutes; but the other half

(for a reason alluded to in the next paragraph) takes a much longer time.

Then, as to the coiling upon contact, in the case first noticed in this

country,[XI-3] in the year 1858, which Mr. Darwin mentions as having led him

into this investigation, the tendril of Sicyos was seen to coil within half

a minute after a stroke with the hand, and to make a full turn or more

within the next minute; furnishing ocular evidence that tendrils grasp and

coil in virtue of sensitiveness to contact, and, one would suppose,

negativing Sachs's recent hypothesis that all these movements are owing "to

rapid growth on the side opposite to that which becomes concave"--a view to

which Mr. Darwin objects, but not so strongly as he might. The tendril of

this sort, on striking some fitting object, quickly curls round and firmly

grasps it; then, after some hours, one side shortening or remaining short

in proportion to the other, it coils into a spire, dragging the stem up to

its support, and enabling the next tendril above to secure a readier hold.

In revolving tendrils perhaps the most wonderful adaptation is that by

which they avoid attachment to, or winding themselves upon, the ascending

summit of the stem that bears them. This they would inevitably do if they

continued their sweep horizontally. But when in its course it nears the

parent

stem the tendril moves slowly, as if to gather strength, then C.~ stiffens

and rises into an erect position parallel with it, and C so passes by the

dangerous point; after which it comes rapidly down to the horizontal

position, in which it moves until it again approaches and again avoids the

impending obstacle.

Climbing plants are distributed throughout almost all the natural orders.

In some orders climbing is the rule, in most it is the exception, occurring

only in certain genera. The tendency of stems to move in circuits--upon

which climbing more commonly depends, and out of which it is conceived to

have been educed--is manifested incipiently by many a plant which does not

climb. Of those that do there are all degrees, from the feeblest to the

most efficient, from those which have no special adaptation to those which

have exquisitely-endowed special organs for climbing. The conclusion reached

is, that the power "is inherent, though undeveloped, in almost every

plant;" "that climbing plants have utilized and perfected a

widely-distributed and incipient capacity, which, as far as we can see, is

of no service to ordinary plants."

Inherent powers and incipient manifestations, useless to their possessors

but useful to their successors--this, doubtless, is according to the order

of Nature; but it seems to need something more than natural selection to

account for it.

XII

DURATION AND

ORIGINATION OF

RACE AND SPECIES--

IMPORT OF SEXUAL REPRODUCTION

I

Do Varieties wear out, or tend to wear out?

(New York Tribune, and American Journal of Science and the Arts, February,

1875)

This question has been argued from time to time for more than half a

century, and is far from being settled yet. Indeed, it is not to be settled

either way so easily as is sometimes thought. The result of a prolonged and

rather lively discussion of the topic about forty years ago in England, in

which Lindley bore a leading part on the negative side, was, if we rightly

remember, that the nays had the best of the argument. The deniers could

fairly well explain away the facts adduced by the other side, and evade the

force of the reasons then assigned to prove that varieties were bound to die

out in the course of time. But if the case were fully re-argued now, it is

by no means certain that the nays would win it. The most they could expect

would be the Scotch verdict, "not proven." And this not because much, if

any, additional evidence of the actual wearing out of any variety has

turned up since, but because a presumption has been raised under which the

evidence would take a bias the other way. There is now in the minds of

scientific men some reason to expect that certain varieties would die out

in the long run, and this might have an important influence upon the

interpretation of the facts. Curiously enough, however, the recent

discussions to which our attention has been called seem, on both sides, to

have overlooked this.