426 



TR YPA NO SO MI 



sequent casting off of the aflagellar end with the remains of the 

 flagellum. The result of this posterior and anterior reduction in 

 length is to produce a rounded body, with a trophonucleus and a 

 kinetonucleus, which surrounds itself with a capsule and forms the 

 latent body or the post-flagellate stage of the life-cycle. These cysts 

 are about 2 to 4 ^ in diameter. 



After a time these bodies become the preflagellate stage, increase 

 in size and length, and' eventually a flagellum grows out from the 

 kinetonucleus and gives rise to the undulating membrane, and 

 thus again forms the usual flagellate stage. 



(b) In the InDerte'brate.~—Glossina morsitans, when fed upon in- 

 fected animals, is capable of spreading the infection mechanically 

 for about twenty-four hours, after which period it ceases to be 

 infective, and remains non-infective for at least fourteen days, 

 after which about 5 per cent, of flies become again infective, when 

 trypanosomes can be demonstrated in its alimentary canal and in 

 itig salivary glands. 



Zoological Distribution. — As mentioned above, this parasite occurs 

 not merely in man and domestic animals, but also in big game. 



Specificity. — ^The question now arises, Is it a good species or not ? 

 First of all, is it T. castellanii ? 



{a) Sero-Diagnosis. — (i) Attachment experiments are very in- 

 constant, and do not distinguish between the two. 



(2) Trypanolysis does not help, being also inconstant. 



(3) C. castellanii is resistant to human serum. C. rhodesiensis is 

 less resistant. 



(6) Crossed Immunity. — An animal having an immunity against 

 C. castellanii can be infected by C. rhodesiensis. The reverse experi- 

 ment has not yet been conducted. 



We may therefore conclude that C. castellanii and C. rhodesiensis 

 are different species. 



Is C. rhodesiensis a variety of C. brucei ? The answer is No, 

 because Laveran has shown that animals immunized against 



2 



Fig. 112. — Castellanella rhodesiensis (Stephens and Fantham). 

 (After Stephens and Fantham.) 

 I, Long narrow form; 2-4, nucleus passing to aflagellar end; 5, nucleus at 



the aflagellar end. 



