THE SCHIZOGONY OF TRYPANOSOMA RVANSI IN THE SPLEEN 

 OF THE VERTEBRATE HOST. 



By Ernest Linwood Walker. 

 {From the Biological Laboratory, Bureau of Science, Manila, P. I.) 



There have been in recent years observations by several in- 

 vestigators that indicate a more complicated developmental cycle 

 of trypanosomes in the vertebrate host than has hitherto been 

 suspected. 



Salvin-Moore and Breinl, in 1907, described the development 

 of round bodies from the trypanosomes in the lungs of rats 

 infected with Trypanosoma gambiense. These bodies are formed 

 at or near the maximum of the multiplication of the trypanosomes 

 in the circulating blood. In their development, there is, ac- 

 cording to these authors, first an interaction between the bleph- 

 aroplast ("extra-nuclear centrosome") and the nucleus of the 

 trypanosome in the form of a stainable band that grows out from 

 the blepharoplast and becomes connected with the nucleus. This 

 band later becomes broken up and disappears, but it is believed 

 that during the process a part of the blepharoplast becomes 

 united with the nucleus. The protoplasm of the trypanosome 

 then becomes separated from the nucleus which lies in a vaculoid 

 space. This vesicle, containing the nucleus and surrounded by 

 a thin layer of protoplasm, becomes detached from the body of 

 the trypanosome which disintegrates. These bodies are stored 

 chiefly in the spleen and bone marrow, and are considered by 

 Salvin-Moore and Breinl as a resistant stage of the trypanosome 

 which persists when the parasites disappear from the peripheral 

 blood and which give rise by development to the new generation 

 of motile trypanosomes that reappear in blood after the lapse 

 of a variable period of time. For this reason these bodies are 

 designated by these authors as "latent bodies." 



Chagas, in 1909, published an account of a new trypanoso- 

 miasis of man in Brazil, South America, which is transmitted by 

 a biting bug {Conorhinus megistus) , and of which the etiologic 



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