NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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sisted in feeding a young specimen of this species with food
with which was mixed mud that teemed with adult rhabdites
and their progeny.
In the course of a few days, the little animal became
obviously ill. It vomited repeatedly, was continually drinking,
and distinctly feverish; its temperature being raised to 102°F.
It grew worse, and was obviously sinking, and, as I had to
leave Grauhati to go on tour, I killed it by a heavy dose of
chloroform, and examined the viscera. All organs were per-
fectly healthy, with the exception of the intestinal canal. The
stomach was patchily reddened just as seen in autopsies on
cases of anchylostomiasis. At first sight, the duodenum seemed
destitute of parasites, but, on placing pieces of the mucous
membrane in a tray of water, under the simple microscope,
countless multitudes of very small nemadotes were seen adhe-
rent to the mucous membrane. They had attained, in some
cases, nearly half the length of an adult Doclimius duodenalis,
but were extremely slender, the generative organs being
still quite indeterminate, and the whole organisation of the
parasite more like an over-grown, immature rhabditis than an
entozoic doclimius, only one or two being sufficiently developed
to admit of the determination of sex, and these were females.
Eor the rest, the remainder of the intestine swarmed with
other parasites. These were twenty specimens of an Ascaris,
which I believe, is identical with the human A. lumbricoides,
large numbers of an Oxyuris, to all appearance, also identical
with that infesting the human subject, a number of Trichoce-
plialus dispar, and one or two specimens of a strongyle worm
which has not as yet been identified. Ova corresponding to
each of these four species had been found in the fasces, pre-
viously to the infection of the monkey by the Dochmius embryos.
The ova of the strongyle would alone have presented any
difficulty, had the experiment been carried further, as its eggs
are so like those of our species that it would have been prac-
tically impossible to distinguish them by microscopical exami-
nation. Meanwhile, a second monkey of the same species had
been fed in the same way. Its dejecta contained the ova of
the ooayurid parasite alone, so that it was better suited for our
purpose than the first. I had to leave Grauhati before the
animal showed any signs of ill-health, and it died a fortnight
after my departure, i.e., less than three weeks after the first
feeding. Unfortunately, Dr. Mullane was also absent from the
station at the time, and the Hospital-Assistant, in whose charge
the animal had been left, neglected to preserve the intestine in
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spirit for my examination. Naturally enough, lie saw nothing
of the worms in the duodenum, as they can only be made out
by careful examination under a lens, so that he found only the
Oxyurides, but there can be no practical doubt that the animal
died from the effects of the invasion of the immense numbers
of embryos it had been, made to swallow. The extent of
development was quite as great as could be expected in an
experiment that had lasted so short a time, so that I felt little
doubt of being able to rear mature parasites whenever time
for the experiment should be at my disposal. After arriving
at Shillong, three more monkeys, of the same species, were
obtained and fed in the same way, except that a much smaller
amount of infected earth was administered, in order to avoid
the death of the animal before the parasites had had time to
reach maturity. No symptoms beyond occasional mild
diarrhoea have been observed in these animals, though they
have failed to get into as good condition as animals, as fully
fed as they have been, might have been expected to do. In.
all three, the ova of Triclwcephali were found in the fasces, as well
as those of the oxyurid, but none of those of Ascarides or of the
strongyle could be found in either. The fasces were examined
at intervals, but, in neither case,- have the ova of Doclimius
duodenaiis made their appearance. Three months after the
feeding, one of the monkeys was killed. The animal was quite
healthy, except that, just as in the previous case, numbers of
nematodes were found adhering to the mucous membrane of the
duodenum, though not of course in anything like the numbers
that were found in the first experiment. They had increased
a good deal in length, but were otherwise but little in advance
of those found in the previous experiment. The sex of all
specimens could, however, now be made out, and it is a very
curious circumstance that over thirty specimens which were
examined microscopically were all females, and a careful search
for small specimens entirely failed to bring to light a single
male. The remaining two monke} 7 's, though four months in
all have elapsed, are still without any sign of Doclimius ova in
their dejecta, so that there does not appear to be any prospec.t
of the worms with which the} 7 " have been infected reaching
maturity.
Only two interpretations can be put on these later experi-
ments, as far so they have gone : either the embryos of Doclimius
duodenaiis take an extremely long time to reach maturity, which
is, on the whole, improbable, or else the parasites are unable to
find a sufficiently congenial home in Macacus rhesus to admit
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of-tlieir attaining maturity. Personally, I incline to the latter
explanation, as it is entirely in accordance with the general
phenomena of parasitism, that a parasite peculiar to one animal
should be incapable of development in another and different
host. Such being the case, I fear that nothing can be hoped for
from further experiments on animals. The circumstance that
three parasites probably identical with species infesting human
beings, viz., Ascarus lumbricoides, Oxyuris vermicularis, and
Irichocephalus dispar find a congenial host in Macacus rhesus
shows that the latter is as favourable a species for our purpose
as we can expect to obtain, though it is possible that better
success might be met with by employing some of the higher,
tailless apes, the difficulty of obtaining monkeys of such
species here precludes the attempt being made at present. Had
I met with these worms, without being aware of the feeding to
which the monkeys had been subjected, I should certainly have
referred it to a genus quite distinct from either Dochmius or
Rhdbdites, and it might be suggested that the worms found are
simian parasites, having no connection whatever with the
Dochmius embryos introduced into the intestinal canal of the
monkeys experimented upon, but the evidence, I think, is fairly
conclusive that this is not the case, In the first place, the
specimens found in the first experiment, where only a short time
had elapsed between the feeding and the examination, were dis-
tinctly less advanced in development than those found in the
experiment where a period of three months had been allowed
to intervene; in the next, there was an obvious relationship
between the number of parasites found and the severity of the
feeding; and, lastly j the immaturity of all specimens found is
strongly against its being a separate species, as in nearly every
case where a parasite passes any portion of its life-cycle in the
intestinal canal, it is during this period that it attains sexual
maturity, so that it is quite exceptional ever to find large
numbers of immature worms free in this situation, and it would
be in the last degree improbable that, under normal circum-
stances, all should prove to be so. The most developed speci-
mens contained, it is true, fairly developed ova, but none of them
gave evidence of having been impregnated, and no ova cor-
responding to them have ever been found in the dejecta of the
animals experimented on, so that I think it will hardly admit of
doubt that we have to do with a case of arrested development,
and that, in the worms so found, we have a phase of the
metamorphosis of the rhabditis embryos, so to speak, crystal-
lized into a permanent condition, the abnormal host affording
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conditions sufficiently favourable to admit of the commence-
ment of the developmental process, but not affording sufficient,,
or sufficiently suitable, nourishment to allow the process- to
proceed beyond the stage we have met with.
While, however, not entirely conclusive, these experiments
go far to prove two points, first, that the normal method of in-
fection is through the agency of rhabdites progeny, and,
secondly, that the worms fasten on to the intestine at once, for,
though the worms have as yet no oral armature like that of the
adult, yet they were always found actually adhering to the
mucous membrane. The mechanism by which this is effected
is not quite clear, but it must be remembered that the oral
end of these worms is far sharper and finer than the small-
est needle ever manufactured, and that the soft structures of
the intestinal mucous membrane can offer but little resistance
to such an organism, boring its way into it, simply as a sharp
body. That this is easily possible is shown by the way in
which 7.ric1iocephalus dispar bores into the mucosa of the
coecum, for this worm, though equally unarmed, and deci-
dedly larger and coarser at the oral extremity, as is well
known, burrows for nearly an inch under the mucous
membrane of the gut. Probably, like this latter worm, the
little nematode, at this stage, feeds upon the serous fluid per-
meating the tissues, and not upon the blood, as they do at
a later stage; at any rate I have found no evidence that
blood forms any part of their food. The first experiment
is also instructive, in showing that the invasion of a large
number of the parasites may give rise to a distinct febrile
attack, and as, in actual practice, infection probably takes
place, in most cases, not once only, biit repeatedly, it shows
how feverish attacks may form a prominent feature during
the earlier stage of anchylostomiasis and therefore of Icdla-azdr
As to the further development of the parasite, it is open to
doubt whether it undergoes all further changes within the
intestine, or effects a temporary encystment in the wall of the
bowel. In Dr. Schulthes's paper, translated by Dr. J. D. Mac-
donald in Dr. Kinsey's pamphlet, there is a note to the effect,
that Griesinzer and Grassi have found specimens encysted in
the sub-mucosa. There would be nothing astonishing in such
a habit, as the very closely allied Sclrostonum tetracanthum
Dies., which infests the large intestine of equine animals,
always behaves in this way, boring into the walls of the intes-
tinal canal soon after gaining admission to its host, and only
emerging from its cyst when sexual maturity has been reached.
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In horses and mules that have died of what was said to be an
outbreak of " surrah," I have recently found myriads of these
worms so encysted, but, in spite of the f amiharity with the patho-
logical appearances so gained, and a most prolonged and careful
search, I have entirely failed to find any trace of such a habit
in cases of anchylostomiasis. In. every post-mortem exam-
ination, a most diligent search was made for encysted worms,
not only with the naked eye, but with the simple microscope,
and every point that appeared at all suspicious was carefully
dissected. In addition to this, considerable areas of intestine,
in the worst case I have yet met with, were examined by the
method of serial sections, but without the least result. Had
encysted worms been present, I am positive that they could not
have been overlooked, and hence I feel some doubt as to such an
occurrence being the normal habit of the worm. Another
argument against it is to be found in the fact that on working
out the life history of Sclrostomum tetracanthum, I found that its
infective rhabdites were provided with a distinct and peculiar
single boring tooth, and it is natural to suppose that a similar
structure would be found in the dochmius rhabditis if
it were addicted to a similar habit.
Of course, it is possible that, in the cases I have had the
opportunity of examining, all the worms had passed through
the stage of encystment and regained the lumen of the intesti-
nal canal. All that can be said is that it is certain that no such
condition was present in either of these cases. With one
exception, however, all these post-mortem examinations were
on cases that had been a considerable time in hospital, and so
debarred from the chance of recent reinfection. The nearest ap-
proach to anything like encystment met with was in searching
over a set of serial sections, some of which showed very young
worms, not much larger or more developed than those found
in the experiments on monkeys, imbedded in blood clot which
filled up recesses between rugae of the mucous coat. In one
instance a distinct erosion of the mucous membrane was
found underlying the clot. This was from the case which
was only a few days in hospital before death.
The case in favour of encystment as a normal occurrence,
may be summed up as follows :—
(1) In two closely-allied species, of similar habits, it has
been proved to occur as a normal part of the
life history.
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(2) All worms found in tlie lumen of the intestine are
almost always adult and full grown.
(3) The fact of but few observers having met with en-
cystment is explicable by the fact that cases in
which autopsis are obtained have been usually
protected from re-infection for some considerable
time by residence in hospital.
(4) Oases not ^infrequently occur in which, after all
worms living within the intestinal canal have
been cleared out by vermifuges, ova re-appear in
the fasces within a short time. I have met with
many such cases, but they are equally explicable
either by re-infection, or inefficient action of the
remedy.
However, it is certainly not common in ordinary post-
mortem examinations, and the point, which is a comparatively
unimportant one, must remain open.
It is clear that, in order to observe it, one must meet with
the fortunate coincidence of death from other causes, in an
early case of anchylostomiasis, or one in which recent reinfection
has happened; indeed it is probable that 'only the former
class of opportunity would serve, as many clinical facts tend
to show that advanced cases, from their inability to afford
the requisite nourishment, do not form a favourable home for
the parasites, so that it is possible that, in such cases, newly-
introduced embryos may, as in monkeys, be unable to proceed
with their normal metamorphoses.
On the whole, I am inclined to believe that encystmeiit
of the newly-introduced worms will prove to be a fact, and
greatly regret that my scanty pathological opportunities have
as yet failed to afford me the opportunity of observing it.
If, indeed, this wandering into the solid tissues of the intesti-
nal wall be a fact, it affords a read)' explanation of the occur-
rence of pyrexial attacks in the earlier stages of anchylosto-
miasis, as such a wholesale wounding of so septic a surface
as that of the lumen of the bowel could hardly fail to cause
more or less septic poisoning: moreover, the analogy of
trichiniasis, where fever is a common accompaniment of the
migration of the worms, would lead us to expect it, quite apart
from theoretical considerations.
The duration of the life of the worm in its parasitic
stage is a point on which, from the nature of the case, only
a surmise can be formed. The failure of all experiments on
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animals makes the production of definite facts an impossibi-
lity. Some authors speak of a year or years, but I believe
such an estimate is much beyond the truth. They have pro-
bably founded this opinion upon the well-known long duration
of individual cases of the disease, but, in so doing, have
quite overlooked the possibility of repeated infections. The
number of available ovum germs in any given worm is, however,
limited, and the rate of production very high, and as analogy
would lead us to expect that the worm would die as soon as
sexual activity became impossible, it can hardly be supposed
that its life can extend over many months.
Another strong argument against the longevity of the
worms is that the number met with, in post-mortem examina-
tions in fatal cases, is often obviously inadequate to account for
the mischief that has been effected, and this can only be explained
on the assumption that, at some period of the case, a very
much larger number were present. Owing to their home
being in the duodendum, worms dying a natural death would
undergo digestion in their passage through nearly the
whole length of the intestinal canal, and would not appear
in the dejecta. That this does not take place when they are
expelled by thymol, is owing to the fact that the worms are
much more often stupefied than killed outright by this drug,
and often still exhibit feeble motions. Those that have been
really killed are always found to be more or less digested.
From these considerations, I believe that the disease has
a natural tendency to cure, but too often the damage
inflicted by the worms during their life has been so serious,
that the patient cannot muster sufficient strength for recovery,
whether they be expelled in the course of nature or by the
action, of vermifuges.
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VII.—EFFECT OF VARIOUS CONDITIONS ON THE LIFE OF THE
FREE STAGE.
Having thus traced what may be termed the normal
life history of the Doclimius rhabdites, it remains to be seen
how they are affected, adversely or otherwise, by external
conditions.
EFFECT OF NOURISHMENT.—Some points in this connection
have already been incidentally noticed, but as various consi-
derations of great practical importance in devising preventive
measures are thereby elucidated, it will be necessary to go
more into detail.
If the worms be supplied with but a limited amount of
their natural food, as happens in the method of cultivation in
feecalized sand, already described, they pass through all the
stages already described, but only a single generation of mature
rhabdites appears. After this the supply of nourishment is
so far exhausted, that the progeny of those which have
reached maturity fail to do the like, and remain in the
undifferentiated, non-sexual stage. So far, however, from
shortening their lives, this deprivation of a free supply of
nourishment, and the attendant arrest of development appears
to greatly prolong it.
As we have seen, with a free supply of nourishment, the
whole duration of life is a matter of only a few days ; but if
development be arrested by exhaustion of the nutritive supply,
the embryos remain, without growing or changing in any
way, for very long periods. What the limit of this may be,
I am unable to say, because my experiments on this point
are still pending. I can only affirm that, after fully six
months, my cultivations seem as rich in embryos as ever.
When in this state, the embryos appear to rarely, if ever,
change their skins, they are sluggish, and move but little, in
fact, they are in that stage which Lutz described as encap-
suled. The term, however, appears alike needless and mis-
leading, for their structure is quite unchanged, and the so-
called capsule is nothing more than the ordinary chitinous
investment common to all nematodes. I have dissected a
great many specimens, and am convinced that nothing what-
ever of the nature of a capsule is present. When first trans-
ferred from damp sand to a tray of water, they are extremely
sluggish, but soon begin to move about actively, and after a
while they again become quiet, and often remain quite motion-
less for days ; but the addition of some stimulating agent to the
H
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water, such as a little salt or alcohol, quickly induces motion,
and convinces one that they are not dead, but resting. It may
be that the comparatively limited supply of air and general
unnaturalness of their surroundings have something to do
with this, for cultivations conducted by pouring the fasces over
an enclosed patch of garden soil behave somewhat differently.
Several experiments were made in this manner, four planks
being nailed together so as to form a bottomless box, about 9
inches square, and sunk in the soil of the garden. Infective fascal
matter, diluted with water, so as to spread easily over the whole
surface, was then poured on the little patch of ground so
marked out, and the rest left to nature. Under these circum-
stances, judging from the normal length of life of the rhabdites
and the length of time during which they continued to appear,
some two or three generations may be expected, but, in the end,
with the exhaustion of the supply of nourishment, the same
state of things is brought about as appeared earlier in cultiva-
tions carried on within the laboratory, though of course the
number of embryos left in the resting stage is much increased.
Development, however, is but arrested, and only awaits a
fresh supply of nourishment to recommence. If we now pour
over such a cultivation some quite uninfected fascal matter,
in a couple of days, mature rhabdites of both sexes appear in
immense numbers and continue to appear as long as the fresh
nutritive supply lasts, after which, the embryos, greatly in-
creased in numbers, sink into the resting stage and may remain
so, as we have seen, for months. After which the process may
be repeated again, with the same result.
The following experiment will illustrate these points:—
Experiment 24-—May 3rd.—On visiting the Shillong dis-
pensary I found a man who was suffering from undoubted symp-
toms of anchylostomiasis. He came from a village near Nong-
poh, on the Gauhdti road, a neighbourhood in which kdla-azdr is
beginning to appear, and had never been employed on a tea-
garden, being 111 fact an ordinary villager. Dr. Campbell had
already recognized the nature of the case, and had treated him
once with thymol. Examination of the fasces, however, showed
that there were still some worms in the intestine, as they con-
tained a considerable number of ova. Some of the dejecta
were placed in a bottle and allowed to remain undisturbed for
two days.
May 5th.—Eggs far advanced in segmentation, but no
embryos. Fasces diluted with water and poured over a patch
of garden soil enclosed between four boards.