TRYPANOSOMA 



57 



malarial parasites had 



FIG. 1 8. Trypanosoma car- 

 assii, Mitr. From the blood of 

 the crusian (Carassius vulgaris), 

 drawn with a blood corpuscle 

 from the host for comparison 

 of size. (After Mitrophanow.) 



been mistaken for trypanosomes. The 

 statement has, however, acquired new 

 importance from the fact that Button 1 

 has observed trypanosomes in the blood 

 of a European. 



Trypanosomes are flagellates of 

 elongated shapfc, which, nevertheless, 

 are capable of changing their form. 

 They bear an undulating membrane on 

 one side along the entire length of the 

 body, and in most cases possess a fla- 

 gellum at one extremity. 



Transmission is effected in the same 

 species by blood-sucking arthropoda ; T. 

 brucei is conveyed by the tsetse fly 

 (Glossina morsitans), T. lewisi by fleas ; 

 the carrier, however, for most species 

 is still unknown. 2 



Trypanosoma. 



The discovery of a trypanosome in sleeping sickness, by Dr. 

 Aldo Castellani, in 1902, has given great pathological importance 

 to the genus Trypanosoma. It is therefore necessary to supple- 

 ment the author's brief mention of this group of parasites with a 

 summary of the most recent information on the subject. 



Trypanosomes, as usually seen in the blood of man and cattle, 

 are elongated, unicellular bodies provided with a kind of fin-fold, 

 the undulating membrane, which runs along the dorsal edge of the 

 body, forming frill-like folds, and terminates in a free whip-like 

 filament, the flagellum, which may vary greatly in length. 

 Stained specimens show very clearly a large nucleus, usually about 

 the middle of the body, and a much smaller chromatin mass 

 placed more or less near one pole. This small mass of chromatin 

 has been, variously termed blepharoplast, micro-nucleus, centrosome. 

 I will use the term blepharoplast as the most appropriate. In 

 fact, it is from this small chromatin mass that arises the flagellum. 

 The extremity of the body which encloses the blepharoplast is the 

 anterior extremity ; it varies greatly in shape at different stages of 



1 Laveran, A., and Mesnil, F., " Du mal. d trypanos. leur repart. d la surface du globe " 

 (Janus, 1902, vii.). 



' ; - Other species of Glossina besides Glossina morsitans carry Trypanosoma brucei. 

 Sleeping sickness (Trypanosoma gambiense) is carried by Glossina palpalis. Surra 

 must be carried by some other biting flies, as Glossinae do not occur in Asia. (F.V.S.). 



