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[JuLy 27, 1899 
in the blood. In the rabbit, in which the organisms are few 
or rare inthe blood, the glands do not show any marked change, 
and the Trypanosoma are not readily found in them. Many 
other forms are found in the glands, to which reference will be 
made below. 
(c) Zn the Spleen.—The adult Trypanosoma is found in but 
small numbers in the spleens of the various animals we have 
examined ; but other forms are found there which will be de- 
scribed later. The enlargement of the spleen is fost mortem 
the most obvious fact in the morbid anatomy of the disease ; 
it may attain even to four or five times the average volumie— 
this is especially the case in the rat. 
(d) In the Bone-marrow.—We have found either very few 
flagellate organisms, or none at all, in the bone-marrow of the 
various animals we have worked with. The marrow is altered 
in colour and structure, but there does not seem to be a greater 
number of Trypanosoma than can be accounted for by the blood 
in the marrow. 
In the other organs and parts, the number of organisms 
present depends upon the relative quantity of blood in the part. 
(2) Ln the Body of Spleenless Antmals,—As the spleen in the 
ordinary animals is the organ which is most obviously altered in 
this disease, we have made a series of inoculations into animals 
(dog, cat, and rabbit) from which the spleen had been removed a 
year ago. In the dog, the adult forms of the Trypanosoma are 
not found so early in the blood of spleenless as in that of 
ordinary animals (seventh day as compared with fourth day after 
inoculation). The glands, after death, are much more generally 
enlarged, and are reddish in colour, and contain many more 
organisms than in the normal animal. Both the blood and 
glands contain, however, numerous other forms to be described 
below. 
This marked difference in the colour of the glands of spleen- 
less animals is probably due to the removal of the spleen, and 
the glands consequently taking on some of the splenic functions. 
The bone-marrow is much altered, and in it likewise are found 
a large number of Trypanosoma, both flagellate and what are 
termed below ‘‘amceboid” forms. 
In the cat the conditions of experiment were altered, the blood 
(1 c.c.) from the infected animal being introduced, with every 
precaution to avoid contamination of the tissues, direct into the 
jugular vein. In this case the organism appeared in the blood 
in numbers on the fourth day, and the animal died on the 
twelfth day. As the Trypanosoma were introduced into the 
blood stream direct, there was no marked glandular enlarge- 
ment, but the glands were all reddish in colour, the change in 
colour being due to the spleenectomy. A few adult organisms 
were found in the glands and in the bone-marrow. 
In the spleenless rabbit a few Trypanosoma have been found 
in the blood on two occasions, but the animal lived nearly two 
months, and notwithstanding the failure to detect adult flagellate 
forms in the blood on numerous occasions, the blood was always 
infective, and contained numerous forms termed ‘‘ amceboid ” 
and “ plasmodial’’ below. 
C. Infectivity. 
(a) In Ordinary Animals.—The blood and organs of an 
animal dead of the disease lose, before twenty-four hours after 
death, their infective power. This is apparently due to the 
rapidity with which decomposition sets in after death, as we 
have found living Trypanosoma in film preparations, made as 
described above, as longas five to six days after removal of the 
blood from the body ; and we have also found that large quan- 
tities (200 c.c.) of blood removed from the body into a sterile 
vessel and kept in an atmosphere of oxygen, retain their 
virulence for at least three days, notwithstanding the fact that 
the flagellate form cannot be demonstrated. 
We have found that the blood of the dog is infective at least 
two days before any adult Trypanosoma can be seen in the 
blood ; and we have also found that the blood of the spleenless 
rabbit, in which we have only on two occasions seen any adult 
forms, is invariably infective. This, of course, suggests the 
idea that the organisms must be present in another form, and 
we have been able, by the use of the method of staining 
described above, to demonstrate the presence of other forms in 
the blood and organs, and have shown, by the experiments just 
mentioned, that the infectivity of the blood, in cases where there 
are no flagellate forms discoverable, depends in all probability 
upon the presence of one of the other forms which the Trypan- 
osoma assumes. 
NO. 1552, VOL. 60] 
‘micro-nucleus. 
Although a differential staining method, such as the one we 
have used, is necessary for following and demonstrating the 
various stages of the life-history of the Trypanosoma, still these 
stages can be seen in unstained living specimens, with very 
careful illumination. Asa matter of fact, our first observation 
of them was in unstained preparations. 
In the blood of the dog, cat, rabbit, rat, and mouse, besides 
the adult forms as described above, which, as mentioned, are 
very various in size, there are adult forms undergoing division, 
both longitudinal and transverse, to which reference will be 
made later. Also two organisms are sometimes seen with their 
micronuclei in close apposition, or fused together, with more or 
less of their bodies also merged together. Such forms we believe 
are conjugations. Again, there are other large forms, with or 
without a flagellum, in which the chromatin of the macronucleus 
is broken up into a number of tiny granules, not bigger often 
than the micronucleus. Besides these there are other forms, 
which we call for convenience here ‘“‘amceboid” forms, by 
which term we mean single, small, irregularly shaped forms, 
with or without a flagellum, but always with a macro- and 
These nuclear structures are generally sur- 
rounded by a very delicate envelope of protoplasm, of greater or 
lesser extent, but occasionally forms are seen which seem to con- 
sist only of chromatin, with or without a flagellum. Besides 
these, again, there are other forms which we call, also for con- 
venience, ‘‘plasmodial ” forms, meaning thereby an aggregation 
or fusion of two or more amoeboid forms. In the blood these 
plasmodia are not generally very large, but may show evidence 
of from two to eight separate elements. Signs of division are 
very common ; but in the blood one does not often meet with a 
plasmodium dividing up into more than four organisms of the 
adult shape. The plasmodial form also retains intact the two 
nuclear structures—the macro- and micro-nucleus—which we 
believe divide in the plasmodium, thus increasing its size. 
In the spleenless animals the blood may contain no forms but 
the amceboid and plasmodial, such as is the case in the rabbit, 
yet this blood is infective; moreover, in the dog, before the 
adult organism appears in it, the blood is infective, and therein, 
at this period, these plasmodial forms can be demonstrated. In 
the glands these plasmodial forms are found, but only in 
quantity in those animals from which the spleen has been 
removed. 
The spleen is the organ which shows these forms in the 
greatest abundance. The whole spleen is crammed in every 
part with plasmodia, which are wedged in between the splenic 
cells in every direction ; many amceboid forms and also imma- 
ture flagellate forms are also seen, but the most striking thing 
is the enormous quantity and uniform distribution of the 
plasmodia. The great enlargement of the spleen, which we 
have found constant in all the animals we have used, is caused 
by this mass of plasmodia, which we have found in the spleen 
within forty-eight hours from the time of inoculation. 
In the marrow these plasmodial forms are only found, so far 
as our experience goes, in those animals from which the spleen 
has been removed. In these cases there are both plasmodial 
and amceboid forms in the marrow, the latter the more 
abundant. 
The principal differences in the distribution of the plasmodial 
forms in animals with and without spleens is this: that in the 
animals with spleens the organ of choice for the plasmodia is the 
spleen, but they are also found constantly in the blood, and in 
less quantity in the glands, whereas in animals from which the 
spleen has been removed the plasmodial forms are plentiful in 
the blood, the glands, and the bone-marrow. 
D. Life-History of the Trypanosoma ‘ Brucii.” 
Besides the forms mentioned above, we have seen in the blood 
and in the organs divisions of the adult form, both longitu- 
dinal and transverse, the former the more frequent; but we 
think that this direct mode of reproduction is far less common 
than the indirect by means of conjugation (probably), breaking 
up of chromatin, production of amceboid forms, with subsequent 
division of these amceboid forms, and the formation of plasmodia 
by the aggregation or fusion of the amceboid forms, and these 
finally giving off flagellate forms, at first small, and gradually 
increasing up to the normal adult form. : 
So that we should tentatively summarise the life-history of 
the Trypanosoma found in Tsetse Fly disease, which we think 
might properly be called ‘* Zxypanosoma Bruct?,” in recognition 
