Microscopic experiments daily demonstrate the existence of myriads of
animalcules in every substance. They have recently been discovered in the
progress of certain crystallizations; and some philosophers maintain that
most inorganic bodies are formed of the remains of organic substances. The
existence of animalcules in the generative secretion was first noticed by
Lewis Hamme, a young German student, and shown by him to Leeuwenhoeck, who
published an account of them. Hartzoeken wrote upon the subject the
following year, and asserted that he had seen these animalcules three
years before they had been observed by Hamme. This curious subject soon
attracted the notice, not only of physiologists, but of priests, artists,
and even courtiers, for we find our Charles II. making curious inquiries
on this investigation. Although many opticians could not discover these
creatures, the eyes of courtiers were more keen than theirs, and to
gratify their royal master's depravity, described them most minutely.
Their length was 3/100000 of an inch, their bulk such as to admit the
existence of 216,000 in a sphere whose diameter was the breadth of a hair,
and their rate of travelling nine inches in the hour. They saw them in
the seminal secretion of every animal; and, what was still more
remarkable, they were of a similar size whatever might have been that of
the animal: they saw them in the sprat and in the whale; they could
distinguish the male from the female; and they all moved along in
gregarious harmony like a flock of sheep: nay, more; Dalenpatius actually
saw one of them, more impatient than his companions, burst from his
ignoble shackles, and actually assume the human form. At other times they
were discovered swimming in shoals to given points, turning back,
separating, meeting again, and frisking about like golden fish in a pond.
Kauw, Boerhaave, Maupertius, Lieuland, Ledermuller, Monro, Nicholas,
Haller, and indeed most of the philosophers of Europe, were convinced of
their existence.
Buffon, however, and other naturalists, contended that these were not
animalcules, but organic particles; and Linnaeus imagined them to be inert
molecules, thrown into agitation by the warmth of the fluid. Finally, to
determine the question, Spallanzani began an assiduous course of
observations and experiments. He found these animalcules in the human
species to be of an oval form, with a tail tapering to a point. This
appendage, by moving from side to side, propelled them forward. They were
in constant motion in every direction. In about twenty-three minutes their
movements became more languid, and in two or three hours they generally
died. The duration of their life, however seemed to depend, in a great
measure, on the temperature of the medium: at 2 deg. (Reaumur) they died
in three quarters of an hour; while at 7 deg. they lived two hours, and at
12-1/2 deg. three hours and three quarters. If the cold was not too
intense, they recovered upon the temperature being raised; when only 3 deg.
or 4 deg., they recovered after a lethargy of fourteen hours; and according
to the less intensity of the cold, they might be made to pass from the
torpid to the active state more frequently. They were destroyed by river,
ice, snow, and rain water; by sulphur, tobacco, camphor, and electricity;
even the air was injurious to them: in close vessels their life was
prolonged to some days, and their movements were not constant and hurried.
They were of various sizes, and perfectly distinct from all species of
animalcules found in vegetable infusions, &c. In short, Spallanzani
completely confirmed the principal observations of Leeuwenhoeck, and
satisfactorily explained the sources of the inaccuracies of other
inquirers. Prevost and Dumas have recently confirmed the observations of
the Italian physiologist.
This doctrine of life being perpetuated by the transmission of animated
particles, or animalcules, is by no means of modern date. We find this
theory advanced by Hippocrates, and Aristotle, and Plato. Democritus
described worms that assumed, in the progress of their development, the
human form; and Lactantius thus refuted his ideas: "Erravit ergo
Democritus, qui vermiculorum modo putavit homines effusos esse de terra,
nullo auctore, nullaque ratione." Hippocrates plainly says, that the
seminal secretion was full of animalcules, whose several parts were
developed, and grew afresh; that nothing did exist that had not
pre-existed; and that what we term birth was nothing more than that
transition of these hitherto imperceptible animalcules from darkness to
light.
Gesner has endeavoured to prove that the word [Greek: psyche], so
frequently found in the writings of Hippocrates, and translated _anima_,
was synonymous with _insectum_, _animalculum_, _papilio_. Plato, when
expressing himself on this curious subject, compares the matrix to a
fertile field, in which animalcules are gradually developed, at first of
such a small size that they are imperceptible, but, by taking the food
prepared for them, grow in strength until they are brought to light in a
state of perfect generation; and St. Augustine thus follows: "Hunc
perfectionis modum sic habent omnes ut cum illo concipiantur atque
nascuntur; sed habent in ratione, non in mole, sicut ipsa jam membra omnia
sunt latenter in semine; cum etiam natis nonnulla desint, sicut dentes, ac
si quid ejusmodi." In the works of Seneca we also find the same notions:
"In semine omnis futuri hominis ratio comprehensa est, et legem barbae et
canorum nondum natus infans habet; totius enim corporis, et sequentis
aetatis, in parvo occultoque lineamenta sunt."
It may be said that these opinions were similar to those of the
_Ovarians_, who, as we have observed already, believed that every thing
arose from the egg. Such were Aristotle, Empedocles, and other
philosophers: "For the egg is the conception," said the first of these
great men, "and after the same manner the animal is created;" but there
was a manifest difference in their systems. Harvey, Haller, De Graef, were
amongst the most warm advocates of this doctrine, which indeed prevails to
the present day, as it would be difficult to find organized beings that
did not spring from an original germ.
It thus appears that, notwithstanding the absurd doctrines of generation
being founded upon the existence of these animalcules, they clearly do
exist. Modern microscopic experiments daily confirm the fact; not only in
the generative secretion, but in the other fluids of the body: creatures
of an inch to an inch and a quarter in length have been found to inhabit
the mesenteric arteries of asses and horses. Mr. Hodgson found them in
seven asses out of nine. They have also been found in the blood of female
frogs, salamanders, and tadpoles. What wonders are perhaps in store for
the microscopic observer and the physiologist! All living matter seems to
be animated by particles, by atoms, equally possessed of life. Does the
vitality of these constituent molecules hold any influence over our
existence? Is their life necessary to the preservation of ours? Is any
agency destructive to them injurious or destructive to us? In a former
paper I have recorded recent observations, where animalcules of a peculiar
description were found in the purulent secretion attending various
affections. A morbid condition seems thus to produce a new series of
animated beings, or this new series of living atoms perhaps have produced
a morbid state. Many eruptive maladies are either caused by the presence
of insects, or insects are subsequently developed in their pustules.
Wichmann, and many other physicians, have maintained that the itch was
produced by an insect of the genus _acarus_, or _tick_.
Latreille has given a minute description of this creature in his _Genera
crustaceorum et insectorum_, and calls this offensive species the
_sarcoptes scabiei_. Linnaeus classed it among the _aptera_, and termed it
the _acarus scabiei_. This insect is nearly round, with eight legs; the
four fore-legs terminated with a small head, the hind ones with a silky
filament. The Arabian Avenzoar had long since observed them, and it was
from his writings that Mouffet was induced to pursue the inquiry. Redi, an
Italian physician, was the first propagator of this doctrine in modern
times, and published, in 1685, a paper of Cestoni of Leghorn, who had
frequently observed mendicants and galley-slaves extracting these insects
from the pustules of itch with the point of a pin, in the same manner as
_chigoes_ are extracted from their cyst in the West Indies.
It was this communication of Cestoni that led to a further and more minute
investigation. Curiosity was every where excited, and the most learned
and intelligent naturalists and physicians, amongst whom we find the
illustrious names of Borelli, Etmuller, Mead, Pringle, Pallas, Bonani,
Linnaeus, Morgagni, strove with incessant diligence to ascertain this
important fact, which certainly was likely to shed a new light on our
pathological speculations. The existence of the acarus was established.
The most conclusive experiments on the subject were those of Gales, in
1812. The following is the account of them: "I placed under a microscope a
watch-glass with a drop of distilled water, after having carefully
ascertained that it did not contain any visible animalcules. I then
extracted from an itch pustule a small portion of the virus, which I
diluted in the water with the point of a lancet. I watched most
attentively for upwards of ten minutes, without having been able to notice
any animation. Two similar experiments were equally ineffectual.
Disappointed in my expectations, I was about giving up the task, when an
idea struck me of submitting the liquid of the first experiment to another
trial. I had left it in the watch-glass, exposed to solar heat. I then was
not a little surprised when I discovered a perfect insect struggling with
its legs to extricate itself from the viscid fluid that confined it.
Having succeeded in reaching a more limpid part of the liquor, its form
was so distinct that Mr. Patrix, who was with me, was enabled to take an
exact drawing of its configuration."
This curious result naturally induced Gales to pursue his inquiries, and
he discovered that this insect chiefly occupies the pustules that are
filled with a thin serum, and avoids those that contain a thicker
secretion. Hence the watery pimples in itch are invariably those that
produce the most intolerable prurience.
The next important question was to decide whether this insect was the
cause of the disgusting disorder. For this purpose Gales placed several of
them on the back of his hand. He then covered the part with a small
watch-glass, kept in place with a bandage. Three hours after he awoke,
experiencing a sensation of itching on the part. The following morning
three itch pustules were evident, and convinced him that he had succeeded
in inoculating himself with the loathsome complaint. This fact he
communicated to Olivier, Dumeril, Latreille, and Richerand. Experiments in
the hospital were immediately directed to be made, and all produced a
similar result; affording a convincing proof that these insects could
produce the affection, which they had merely been thought to have
complicated.
Many writers, who, like Mason Good, had decided that "whenever these
insects appear, they are not a cause but a consequence of the disease,"
opposed and contradicted the statement of Gales, and the numerous
practitioners who had procured and witnessed facts, which are never
"stubborn things" to speculative minds. These writers maintained that
whenever any organ was weakened, or in a morbid condition, it was apt to
become a nidus for some insects or worms to burrow in. Hence the numerous
varieties of invermination in debility of the digestive organs. But it is
needless to observe that their objections cannot stand against the
imbodied evidence brought forward in proof of their error. Bosc, Huzard,
Latreille, Dumeril, and many other naturalists, subsequently found these
acari in the eruptive diseases of many animals.
I repeat it, this subject is replete with interest; and microscopic
experiments may some time or other throw a material light on the practice
of medicine. Those substances that are known to destroy the insect that
produces the itch, cure the malady. May not this analogy lead to singular
results?