48
as those which he found in the surra disease at Dera Ismail Khan ; he does not think
they belong to any class of spirilla, but that they occasionally take a spiral form like an,
eel or a serpent in contortion. He further informs me that, after examining them with
a 1/12 immersion lense, he found their bodies not really round, but flattened, the sides often
curl in, which gives them a roundish appearance.*
Varieties.—The parasites as taken from the mule, pony, dog, and monkey differ
a little in minor details of structure, such as sharpness of the " head " end. and so on ;
also in strength, energy, and ferocity.
Movements.—Eel-like, lashing, vermiform; less frequently spiral, observable
especially in the parasite from the dog and when the movement is very slow. I have
seen in some of my cases the very small parasites spinning round and round on a
refrangent thickening apparently at about the centre of the body. Perhaps this is the
early stage of spirilloids when they are in a transition from spherical to spiral or sub-
spiral forms. But we have no exact evidence that spirilloids ever assume a germ form.
Action and habitat.—We have no evidence as yet of an extra-sanguinal abode of the
spirilloids or of connection of the pathological with innocent spirillum forms such as are
found in stagnant water, and so on, nor with the very closely allied bodies found in the
blood of rats. They cause considerable destruction of the red elements of the blood,
irritation of organs through which that blood circulates, and blocking of vessels with
its sequelae. Koch has cultivated spirilla of man artificially, and I notice a little
growth on some of my slides.
Food and other nutritive essentials are furnished by the living blood, but what they
exactly are is not established. It is remarkable that the parasites attack the red elements
only; in all my microscopical examinations I have failed to detect them in lymph, lymph
glands, spleen pulp, dropsical fluids, and secretions. It would seem as if a certain
temperature sufficed for their destruction, or more correctly to make them assume the
undistinguished form, and that in this way the relapses are brought about.
Excretions.—In our deficient state of knowledge as to the forms assumed by the
parasite, it is premature to discuss whether it is the actual presence and activity of the
parasite which causes the fever and the organism which is in itself the materies morbi,
or whether the fever and the disease depend on the excretion into the blood by spirilloid
of pathogenic matter. The evidence is strongly in favor of the former view; the fact
that blood not containing appreciable spirilloids communicates the disease may be con-
strued into the statement that we have not yet detected the parasite in it. Often,
after prolonged examination of a specimen of blood, we detect just one or two parasites
in it, but we almost always, when the spirilloids are not present, observe spherical nuclei
with independent motile powers.
3. Reproduction and phases of development.—Nothing is known but this—that,
some five or six days after introduction of the parasites into the subcutaneous areolar
tissue and longer after ingestion through the stomach, 0 there are many more parasites
in the system than were introduced artificially. They cause local irritation at the seat
of injection, as was proved in my inoculations of the bullock and monkey, and the
latter case showed that such local irritation does not involve failure of the experiment
to produce systemic infection. Parasites introduced into the system therefore
reproduce freely ; we have no evidence that this takes place in the lymphatic system,
but rather infer that it occurs in the blood. A growth of the parasites in the blood
seems to be indicated by some being larger than others. We have some indications
of development in that fluid. Although, possibly, the spirilloids are viviparous, the
balance of evidence seems at present in favor of their being in the non-irritant phases
of the disease spherical nucleoid bodies and of the spirilloids being in due course, i e.,
some four or five days, developed from these; thus may be explained the longer
incubation with inoculation of blood parasites not detectable, than with blood parasites
free and active. Sometimes in the phase of fall of temperature masses of debris seem to
have pieces of spirilloids attached to them which may be the latter degenerating. Igna-
tovsky found head-like bacteria, filaments of point-like micrococci which were aggluti-
nated by means of thin stripes of a homogeneous, structureless substance, having a slow
wave or pendulum-like movement, but I have never been able to find any in my cases.
*In paragraphs 33 and 34 of his report on "Surra" he observes " when the parasite dies slowly in serum its body
spreads out and flattens. "
† Inoculations made simultaneously and in the same way and with the same instruments caused in mules no local
disturbance.