On the Organism found in the Tsetse Fly Disease. 279 



matin 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 " amoeboid " forms, by which 

 term we mean single, small, irregularly shaped forms, with or without a 

 flagellum, but always with a macro- and micro-nucleus. These nuclear 

 structures are generally surrounded by a very delicate envelope of 

 protoplasm, of greater or lesser extent, but occasionally forms are seen 

 which seem to consist 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 

 amoeboid 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 plas- 

 modia, which are wedged in between the splenic cells in every direc- 

 tion : many anoeboid forms, and also immature 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 onr 

 experience goes, in those animals from which the spleen has been 

 removed. In these cases there are both plasmodial and amoeboid 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. 



