140 TRYPANOSOMIASES OF RHODESIA. 



the trypanosome is a plastic body, swimming in a medium var}'- 

 ing in viscidity, specific gravity and chemical composition ; the 

 examination of the details of the parasite requires the adoption 

 of certain methods of technique which vary with different 

 workers, and are open to discrepancies attributable to the in- 

 dividual factor of the operator. Even with the same worker, 

 using the same methods, results vary to a considerable degree, 

 and many other controlling tests are required before one is justi- 

 fied in declaring the identity of the organism under dbservation. 

 r.ut it must not be thought that 1 am endeavouring to dis- 

 count the value of exact study into morphology and the in- 

 formation derived thereby. Bruce, while lamenting the tendency 

 towards multiplying unnecessarily the number of species, offers 

 also an excuse for precise study of morphology in conjunction 

 with other tests on the grounds that 



" if there is some well-marked difference in two trypanosomes, even if 

 alike in shape, such as their power of setting up disease in certain 

 animals, their mode of spreading from the sick to the healthy — it may 

 be in one by ' tsetse ilies,' in another by Stomoxys or Tobaiius, or by 

 other means — then, naturally- it is of great practical use to distinguisli 

 them l)y different specific names-" 



But close attention to the morphology or appearance of the 

 parasite is also of great value in another connection. The theor}^ 

 I advanced as to the possibility of variations in shape being 

 brought about by conditions unfavourable to the parasite has 

 recently received confirmation from several authorities working 

 in the field of therapeutics. 



Nuttall observed degenerative changes in Tr. hnicci con- 

 sequent upon arsenopheiT\-lglycin treatment. He found that : 



" whereas before treatment 95 per cent- showed blue-staining protoplasm 

 protruding beyond the biepharoplast in the characteristic beak-like man- 

 ner, already one hour after treatment only five per cent- of the parasites 

 were free from granules, and, none showed the beak-like process pos- 

 teriorly- After two hours all the trypanosomes showed granules- After 

 three hours - - - nine per cent- had become rounder or were l^reaking 

 up." 



Thomas made similar observations after the administration 

 of atoxyl, and Hindle has obtained similar results with Tr. gam- 

 biciisc after treatment with arsenophenylglycin. In the clinical 

 study of a case, therefore, such variations may be found to 

 aff'ord indications as to — 



[a] The natural resistance of the patient. 



( /' ) The virulence of the parasite. 



( (• ) The effect of remedial agents applied. 



The complete life-c}-cle of the trypanosome has not been 

 definitely worked out. although, as we shall see later, it is a 

 matter of practical importance. 



In the peripheral blood the usual method of increase is 

 multiplication by longitudinal division. The kineto-nucleus 

 divides by mitosis followed by mitotic division of the tropho- 

 nucleus. 



