Observations on Nature in the Tropics--The Dung Beetle--The
Mason-fly--Spiders--Luminous Insects--Efforts of a Naturalist--Dogs
Worried by Leeches--Tropical Diseases--Malaria--Causes of
Infection--Disappearance of the "Mina"--Poisonous Water--Well-digging
Elephants.
How little can the inhabitant of a cold or temperate climate appreciate
the vast amount of "life" in a tropical country. The combined action
of light, heat and moisture calls into existence myriads of creeping
things, the offspring of the decay of vegetation. "Life" appears to
emanate from "death"--the destruction of one material seems to multify
the existence of another--the whole surface of the earth seems busied
in one vast system of giving birth.
An animal dies--a solitary beast--and before his unit life has vanished
for one week, bow many millions of living creatures owe their birth to
his death? What countless swarms of insects have risen from that one
carcase!--creatures which never could have been brought into existence
were it not for the presence of one dead body which has received and
hatched the deposited eggs of millions that otherwise would have
remained unvivified.
Not a tree falls, not a withered flower droops to the ground, not a
fruit drops from the exhausted bough, but it is instantly attacked by
the class of insect prepared by Nature for its destruction. The white
ant scans a lofty tree whose iron-like timber and giant stem would seem
to mock at his puny efforts; but it is rotten at the core and not a
leaf adorns its branches, and in less than a year it will have fallen
to the earth a mere shell; the whole of the wood will have been
devoured.
Rottenness of all kinds is soon carried from the face of the land by
the wise arrangements of Nature for preserving the world from plagues
and diseases, which the decaying and unconsumed bodies of animals and
vegetables would otherwise engender.
How beautiful are all the laws of Nature! how perfect in their details!
Allow that the great duty of the insect tribe is to cleanse the earth
and atmosphere from countless impurities noxious to the human race, how
great a plague would our benefactors themselves become were it not for
the various classes of carnivorous insects who prey upon them, and are
in their turn the prey of others! It is a grand principle of continual
strife, which keeps all and each down to their required level.
What a feast for an observant mind is thus afforded in a tropical
country! The variety and the multitude of living things are so great
that a person of only ordinary observation cannot help acquiring a
tolerable knowledge of the habits of some of the most interesting
classes. In the common routine of daily life they are continually in
his view, and even should he have no taste for the study of Nature and
her productions, still one prevailing characteristic of the insect
tribe must impress itself upon his mind. It is the natural instinct
not simply of procreating their species, but of laying by a provision
for their expected offspring. What a lesson to mankind! what an
example to the nurtured mind of mail from one of the lowest classes of
living things!
Here we see no rash matrimonial engagements; no penniless lovers
selfishly and indissolubly linked together to propagate large families
Of starving children. Ail the arrangements of the insect tribe, though
prompted by sheer instinct are conducted with a degree of rationality
that in some cases raises the mere instinct of the creeping thing above
the assumed "reason" of man.
The bird builds her nest and carefully provides for the comfort of her
young long ere she lays her fragile egg. Even look at that
vulgar-looking beetle, whose coarse form would banish the idea of any
rational feeling existing in its brain--the Billingsgate fish-woman of
its tribe in coarseness and rudeness of exterior (Scarabaeus
carnifex)--see with what quickness she is running backward, raised
almost upon her head, while with her bind legs she trundles a large
ball; herself no bigger than a nutmeg, the ball is four times the size.
There she goes along the smooth road. The ball she has just
manufactured from some fresh-dropped horse-dung; it is as round as
though turned by a lathe, and, although the dung has not lain an hour
upon the ground, she and her confederates have portioned out the spoil,
and each has started off with her separate ball. Not a particle of
horsedung remains upon the road. Now she has rolled the ball away from
the hard road, and upon the soft, sandy border she has stopped to rest.
No great amount of rest; she plunges her head into the ground, and with
that shovel-like projection of stout horn she mines her way below: she
has disappeared even in these few seconds.
Presently the apparently deserted ball begins to move, as though acted
on by some subterranean force; gradually it sinks to the earth, and it
vanishes altogether.
Some persons might imagine that she feeds upon the ordure, and that she
has buried her store as a dog hides a bone; but this is not the case;
she has formed a receptacle for her eggs, which she deposits in the
ball of dung, the warmth of which assists in bringing the larvae into
life, which then feed upon the manure.
It is wonderful to observe with what rapidity all kinds of dung are
removed by these beetles. This is effected by the active process of
rolling the loads instead of carrying, by which method a large mass is
transported at once.
The mason-fly is also a ball-maker, but she carries her load and builds
an elaborate nest. This insect belongs to the order "Hymenoptera," and
is of the Ichneumon tribe, being a variety of upward of four hundred
species of that interesting fly.
The whole tribe of Ichneumon are celebrated for their courage; a small
fly will not hesitate to attack the largest cockroach, who evinces the
greatest terror at sight of his well-known enemy; but the greatest
proof of valor in a fly is displayed in the war of the ichneumon
against the spider.
There is a great variety of this insect in Ceylon, from the large black
species, the size of the hornet down to the minute tinsel-green fly, no
bigger than a gnat; but every one of these different species wages
perpetual war against the arch enemy of flies.
In very dry weather in some districts, when most pools and water-holes
are dried up, a pail of water thrown upon the ground will as assuredly
attract a host of mason-flies as carrion will bring together
"blow-flies." They will be then seen in excessive activity upon the wet
earth, forming balls of mud, by rolling the earth between their fore
feet until they have manufactured each a pill. With this they fly away
to build their nest, and immediately return for a further supply.
The arrangement of the nest is a matter of much consideration, as the
shape depends entirely upon the locality in which it is built: it may
be in the corner of a room, or in a hole in a wall, or in the hollow of
a bamboo; but wherever it is, the principle is the same, although the
shape of the nest may vary. Everything is to be hermetically sealed.
The mason-fly commences by flattening the first pill of clay upon the
intended site (say the corner of a room); she then spreads it in a thin
layer over a surface of about two inches, and retires for another ball
of clay. This she dabs upon the plastic foundation, and continues the
apparently rude operation until some twenty or thirty pills of clay are
adhering at equal distances. She then forms these into a number of
neat oval-shaped cells, about the size of a wren's egg, and in each
cell she deposits one egg. She then flies off in search of spiders,
which are to be laid tip in stores within the cells as food for the
young larvae, when hatched.
Now the transition from the larva to the fly takes place in the cell,
and occupies about six weeks from the time the egg is first laid; thus,
as the egg itself is not vivified for some weeks after it is deposited,
the spiders have to be preserved in a sound and fresh state during that
interval until the larva is in such an advanced stage as to require
food.
In a tropical country every one knows that a very few hours occasion
the putrefaction of all dead animal substances; nevertheless these
spiders are to be kept fresh and good, like our tins of preserved
meats, to be eaten when required.
One, two, or even three spiders, according to their size, the mason-fly
deposits in each cell, and then closes it hermetically with clay. The
spiders she has pounced upon while sunning themselves in the centre of
their delicate nets, and they are hurried off in a panic to be
converted into preserved provisions. Each cell being closed, the whole
nest is cemented over with a thick covering of clay. In due time the
young family hatch, eat their allowance of spiders, undergo their
torpid change, and emerge from their clay mansion complete mason-flies.
Every variety of Ichneumon, however (in Ceylon), chooses the spider as
the food for its young. It is not at all uncommon to find a gun well
loaded with spiders, clay and grubs, some mason-fly having chosen the
barrel for his location. A bunch of keys will invite a settlement of
one of the smaller species, who make its nest in the tube of a key,
which it also fills with minute spiders.
In attacking the spider, the mason-fly his a choice of his antagonist,
and he takes good care to have a preponderance of weight on his own
side. His reason for choosing this in preference to other insects for
a preserved store may be that the spider is naturally juicy, plump and
compact, combining advantages both for keeping and packing closely.
There are great varieties of spiders in Ceylon, one of which is of such
enormous size as to resemble the Aranea avicularia of America. This
species stands on an area of about three inches, and never spins a web,
but wanders about and lives in holes; his length of limb, breadth of
thorax and powerful jaws give him a most formidable appearance. There
is another species of a large-sized spider who spins a web of about two
and a half feet in diameter. This is composed of a strong, yellow,
silky fibre, and so powerful is the texture that a moderate-sized
walking-cane thrown into the web will be retained by it. This spider is
about two inches long, the color black, with a large yellow spot upon
the back, and the body nearly free from hair.
Some years ago an experiment was made in France of substituting the
thread of the spider for the silk of the silkworm: several pairs of
stockings and various articles were manufactured with tolerable success
in this new material, but the fibre was generally considered as too
fragile.
A sample of such thread as is spun by the spider described could not
have failed to produce the desired result, as its strength is so great
that it can be wound upon a card without the slightest care required in
the operation. The texture is far more silky than the fibre commonly
produced by spiders, which has more generally the character of cotton
than of silk.
Should this ever be experimented on, a question might arise of much
interest to entomologists, whether a difference in the food of the
spider would affect the quality of the thread, as is well known to be
the case with the common silkworm.
A Ceylon night after a heavy shower of rain is a brilliant sight, when
the whole atmosphere is teeming with moving lights bright as the stars
themselves, waving around the tree-tops in fiery circles, now threading
like distant lamps through the intricate branches and lighting up the
dark recesses of the foliage, then rushing like a shower of sparks
around the glittering boughs. Myriads of bright fire-flies in these
wild dances meet their destiny, being entangled in opposing spiders'
webs, where they hang like fairy lamps, their own light directing the
path of the destroyer and assisting in their destruction.
There are many varieties of luminous insects in Ceylon. That which
affords the greatest volume of light is a large white grub about two
inches in length, This is a fat, sluggish animal, whose light is far
more brilliant than could be supposed to emanate from such a form.
The light of a common fire-fly will enable a person to distinguish the
hour on a dial in a dark night, but the glow from the grub described
will render the smallest print so legible that a page may be read with
case. I once tried the experiment of killing the grub, but the light
was not extinguished with life, and by opening the tail, I squeezed out
a quantity of glutinous fluid, which was so highly phosphorescent that
it brilliantly illumined the page of a book which I had been reading by
its light for a trial.
All phosphorescent substances require friction to produce their full
volume of light; this is exemplified at sea during a calm tropical
night, when the ocean sleeps in utter darkness and quietude and not a
ripple disturbs the broad surface of the water. Then the prow of the
advancing steamer cuts through the dreary waste of darkness and awakens
into fiery life the spray which dashes from her sides. A broad stream
of light illumines the sea in her wake, and she appears to plough up
fire in her rush through the darkened water.
The simple friction of the moving mass agitates the millions of
luminous animalcules contained in the water; in the same manner a fish
darting through the sea is distinctly seen by the fiery course which is
created by his own velocity.
All luminous insects are provided with a certain amount of
phosphorescent fluid, which can be set in action at pleasure by the
agitation of a number of nerves and muscles situated in the region of
the fluid and especially adapted to that purpose. It is a common
belief that the light of the glow-worm is used as a lamp of love to
assist in nocturnal meetings, but there can be little doubt that the
insect makes use of its natural brilliancy without any specific
intention. It is as natural for the fire-fly to glitter by night as
for the colored butterfly to be gaudy by day.
The variety of beautiful and interesting insects is so great in Ceylon
that an entomologist would consider it a temporary elysium; neither
would he have much trouble in collecting a host of different species
who will exhibit themselves without the necessity of a laborious
search. Thus, while he may be engaged in pinning out some rare
specimen, a thousand minute eye-flies will be dancing so close to his
eyeballs that seeing is out of the question. These little creatures,
which are no larger than pin's heads, are among the greatest plagues in
some parts of the jungle; and what increases the annoyance is the
knowledge of the fact that they dance almost into your eyes out of
sheer vanity. They are simply admiring their own reflection in the
mirror of the eye; or, may be, some mistake their own reflected forms
for other flies performing the part of a "vis-à-vis" in their
unwearying quadrille.
A cigar is a specific against these small plagues, and we will allow
that the patient entomologist has just succeeded in putting them to
flight and has resumed the occupation of setting out his specimen. Ha!
see him spring out of his chair as though electrified. Watch how,
regardless of the laws of buttons, he frantically tears his trowsers
from his limbs; he has him! no he hasn't!--yes he has!--no--no,
positively he cannot get him off. It is a tick no bigger than a grain
of sand, but his bite is like a red-hot needle boring into the skin.
If all the royal family had been present, he could not have refrained
from tearing off his trowsers.
The naturalist has been out the whole morning collecting, and a pretty
collection he has got--a perfect fortune upon his legs alone. There
are about a hundred ticks who have not yet commenced to feed upon him;
there are also several fine specimens of the large flat buffalo tick;
three or four leeches are enjoying themselves on the juices of the
naturalist; these he had not felt, although they had bitten him half an
hour before; a fine black ant has also escaped during the recent
confusion, fortunately without using his sting.
Oil is the only means of loosening the hold of a tick; this suffocates
him and he dies; but he leaves an amount of inflammation in the wound
which is perfectly surprising in so minute an insect. The bite of the
smallest species is far more severe than that of the large buffalo or
the deer tick, both of which are varieties.
Although the leeches in Ceylon are excessively annoying, and numerous
among the dead leaves of the jungle and the high grass, they are easily
guarded against by means of leech-gaiters: these are wide stockings,
made of drill or some other light and close material, which are drawn
over the foot and trowsers up to the knee, under which they are
securely tied. There are three varieties of the leech: the small
jungle leech, the common leech and the stone leech. The latter will
frequently creep up the nostrils of a dog while he is drinking in a
stream, and, unlike the other species, it does not drop off when
satiated, but continues to live in the dog's nostril. I have known a
leech of this kind to have lived more than two months in the nose of
one of my hounds; he was so high up that I could only see his tail
occasionally when lie relaxed to his full length, and injections of
salt and water had no effect on him. Thus I could not relieve the dog
till one day when the leech descended, and I observed the tail working
in and out of the nostril; I then extracted him in the usual way with
the finger and thumb and the tail of the coat.
I should be trespassing too much upon the province of the naturalist,
and attempting more than I could accomplish, were I to enter into the
details of the entomology of Ceylon; I have simply mentioned a few of
those insects most common to the every-day observer, and I leave the
description of the endless varieties of classes to those who make
entomology a study.
It may no doubt appear very enticing to the lovers of such things, to
hear of the gorgeous colors and prodigious size of butterflies, moths
and beetles; the varieties of reptiles, the flying foxes, the gigantic
crocodiles; the countless species of waterfowl, et hoc genus omne; but
one very serious fact is apt to escape the observation of the general
reader, that wherever insect and reptile life is most abundant, so sure
is that locality full of malaria and disease.
Ceylon does not descend to second-class diseases: there is no such
thing as influenza; whooping-cough, measles, scarlatina, etc., are
rarely, if ever, heard of; we ring the changes upon four first-class
ailments--four scourges, which alternately ascend to the throne of
pestilence and annually reduce the circle of our friends--cholera,
dysentery, small-pox and fever. This year (1854) there has been some
dispute as to the routine of succession; they have accordingly all
raged at one time.
The cause of infection in disease has long been a subject of
controversy among medical men, but there can be little doubt that,
whatever is the origin of the disease, the same is the element of
infection. The question is, therefore, reduced to the prime cause of
the disease itself.
A theory that animalcules are the cause of the various contagious and
infectious disorders has created much discussion; and although this
opinion is not generally entertained by the faculty, the idea is so
feasible, and so many rational arguments can be brought forward in its
support, that I cannot help touching upon a topic so generally
interesting.
In the first place, nearly all infectious diseases predominate in
localities which are hot, damp, swampy, abounding in stagnant pools and
excluded from a free circulation of air. In a tropical country, a
residence in such a situation would be certain death to a human being,
but the same locality will be found to swarm with insects and reptiles
of all classes.
Thus, what is inimical to human life is propitious to the insect tribe.
This is the first step in favor of the argument. Therefore, whatever
shall tend to increase the insect life must in an inverse ratio war
with human existence.
When we examine a drop of impure water, and discover by the microscope
the thousands of living beings which not only are invisible to the
naked eye, but some of whom are barely discoverable even by the
strongest magnifying power, it certainly leads to the inference, that
if one drop of impure fluid contains countless atoms endowed with
vitality, the same amount of impure air may be equally tenanted with
its myriads of invisible inhabitants.
It is well known that different mixtures, which are at first pure and
apparently free from all insect life, will, in the course of their
fermentation and subsequent impurity, generate peculiar species of
animalcules. Thus all water and vegetable or animal matter, in a state
of stagnation and decay, gives birth to insect life; likewise all
substances of every denomination which are subjected to putrid
fermentation. Unclean sewers, filthy hovels, unswept streets, unwashed
clothes, are therefore breeders of animalcules, many of which are
perfectly visible without microscopic aid.
Now, if some are discernible by the naked eye, and others are detected
in such varying sizes that some can only just be distinguished by the
most powerful lens, is it not rational to conclude that the smallest
discernible to human intelligence is but the medium of a countless
race? that millions of others still exist, which are too minute for any
observation?
Observe the particular quarters of a city which suffers most severely
during the prevalence of an epidemic, In all dirty, narrow streets,
where the inhabitants are naturally of a low and uncleanly class, the
cases will be tenfold. Thus, filth is admitted to have at least the
power of attracting disease, and we know that it not only attracts, but
generates animalcules; therefore filth, insects and disease are ever to
be seen closely linked together.
Now, the common preventives against infection are such as are
peculiarly inimical to every kind of insect; camphor, chloride of lime,
tobacco-smoke, and powerful scents and smokes of any kind. The first
impulse on the appearance of an infectious disease is to purify
everything as much as possible, and by extra cleanliness and
fumigations to endeavor to arrest its progress. The great purifier of
Nature is a violent wind, which usually terminates an epidemic
immediately; this would naturally carry before it all insect life with
which the atmosphere might be impregnated, and the disease disappears
at the same moment. It will he well remembered that the plague of
locusts inflicted upon Pharaoh was relieved in the same manner: "And
the Lord turned a mighty strong west wind, which took away the locusts
and cast them into the Red Sea; there remained not one locust in all
the coasts of Egypt."
Every person is aware that unwholesome air is quite poisonous to the
human system as impure water; and seeing that the noxious qualities of
the latter are caused by animalcules, and that the method used for
purifying infected air are those most generally destructive to insect
life, it is not irrational to conclude that the poisonous qualities of
bad water and bad air arise from the same cause.
Man is being constantly preyed upon by insects; and were it not for
ordinary cleanliness, he would become a mass of vermin; even this does
not protect him from the rapacity of ticks, mosquitoes, fleas and many
others. Intestinal worms feed on him within, and, unseen, use their
slow efforts for his destruction.
The knowledge of so many classes which actually prey upon the human
system naturally leads to the belief that many others endowed with the
same propensities exist, of which we have at present no conception.
Thus, different infectious disorders might proceed from peculiar
species of animalcules, which, at given periods, are wafted into
certain countries, carrying pestilence and death in their invisible
course.
A curious phenomenon has recently occurred at Mauritus, where that
terrible scourge, the cholera, has been raging with desolating effect.
There is a bird in that island called the "martin," but it is more
property the "mina." This bird is about the size of the starling, whose
habits its possesses in a great degree. It exists in immense numbers,
and is a grand destroyer of all insects. On this account it is seldom
or never shot at, especially as it is a great comforter to all cattle,
whose hides it entirely cleans from ticks and other vermin, remaining
for many hours perched upon the back of one animal, while its bill is
actively employed in searching out and destroying every insect.
During the prevalence of the cholera at Mauritius these birds
disappeared. Such a circumstance had never before occurred, and the
real cause of their departure is still a mystery.
May it not have been, that some species of insect upon which they fed
had likewise migrated, and that certain noxious animalcules, which had
been kept down by this class, had thus multiplied within the atmosphere
until their numbers caused disease? All suppositions on such a subject
must, however, remain in obscurity, as no proof can be adduced of their
correctness. The time may arrive when science may successfully grapple
with all human ailments, but hitherto that king of pestilence, the
"cholera," has reduced the highest medical skill to miserable
uncertainty.
Upon reconsidering the dangers of fevers, dysentery, etc., in the
swampy and confined districts described, the naturalist may become
somewhat less ardent in following his favorite pursuit. Of one fact I
can assure him that no matter how great the natural strength of his
constitution, the repeated exposure to the intense heat of the sun, the
unhealthy districts that he will visit, the nights redolent of malaria,
and the horrible water that he must occasionally drink, will gradually
undermine the power of the strongest man. Both sportsman and
naturalist in this must share alike.
No one who has not actually suffered from the effect can appreciate the
misery of bad water in a tropical country, or the blessings of a cool,
pure draught. I have been in districts of Ceylon where for sixteen or
twenty miles not a drop of water is to be obtained fit for an animal to
drink; not a tree to throw a few yards of shade upon the parching
ground; nothing but stunted, thorny jungles and sandy, barren plains as
far as the eye can reach; the yellow leaves crisp upon the withered
branches, the wild fruits hardened for want of sap, all moisture robbed
from vegetation by the pitiless drought of several months.
A day's work in such a country is hard indeed carrying a heavy rifle
for some five-and-twenty miles, sometimes in deep sand, sometimes on
good ground, but always exposed to the intensity of that blaze, added
to the reflection from the sandy soil, and the total want of fresh air
and water. All Nature seems stagnated; a distant pool is seen, and a
general rush takes place toward the cheering sight. The water is
thicker than pea soup, a green scum floats through the thickened mass,
and the temperature is upward of 130 Fahrenheit. All kinds of insects
are swarming in the putrid fluid, and a saltish bitter adds to its
nauseating flavor. I have seen the exhausted coolies spread their dirty
cloths on the surface, and form them into filters by sucking the water
through them. Oh for a glass of Newera Ellia water, the purest and
best that ever flows, as it sparkles out of the rocks on the
mountain-tops! what pleasure so perfect as a long, deep and undisturbed
draught of such cold, clear nectar when the throat is parched with
unquenchable thirst!
In some parts of Ceylon, especially in the neighborhood of the coast,
where the land is flat and sandy, the water is always brackish, even
during the rainy season, and in the dry months it is undrinkable.
The natives then make use of a berry for cleansing it and precipitating
the impurities. II know the shrub and the berry well, but it has no
English denomination. The berries are about the size of a very large
pea, and grow in clusters of from ten to fifteen together, and one
berry is said to be sufficient to cleanse a gallon of water. The
method of using them is curious, although simple. The vessel which is
intended to contain the water, which is generally an earthen chatty, is
well rubbed in the inside with a berry until the latter, which is of a
horny consistency, like vegetable ivory, is completely worn away. The
chatty is then filled with the muddy water, and allowed to stand for
about an hour or more, until all the impurities have precipitated to
the bottom and the water remains clear.
I have constantly used this berry, but I certainly cannot say that the
water has ever been rendered perfectly clear; it has been vastly
improved, and what was totally undrinkable before has been rendered fit
for use; but it has at the best been only comparatively good; and
although the berry has produced a decided effect, the native accounts
of its properties are greatly exaggerated.
During the prolonged droughts, many rivers of considerable magnitude
are completely exhausted, and nothing remains but a dry bed of said
between lofty banks. At these seasons the elephants, being hard
pressed for water, make use of their wonderful instinct by digging
holes in the dry sand of the river's bed; this they perform with the
horny toes of their fore feet, and frequently work to a depth of three
feet before they discover the liquid treasure beneath. This process of
well-digging almost oversteps the boundaries of instinct and strongly,
savors of reason, the two powers being so nearly connected that it is
difficult in some cases to define the distinction. There are so many
interesting cases of the wonderful display of both these attributes in
animals, that I shall notice some features of this subject in a
separate chapter.