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Transactions of the Society. 



parasite and the curling of the flagellum, in the stained prepara- 

 tions, it was difficult to make exact measurements, but I was able 

 to ascertain that the average width, according to whether the 

 membrane was visible or not, varied from 1 to 2 /j, and the length 

 of the body from 20 to 30 /x. The flagellum was about the same 

 length as the body. 



Here and there in a stained preparation there were the forms 

 already described by Evans resulting from the fusion of two para- 

 sites. But the union obviously took place by the non-flagellated 

 ends, for the two flagella were frequently turned in the same direc- 

 tion, so that the fused parasites resembled, as Dr. Evans sub- 

 sequently suggested, a trophy of buffalo horns (Photo 11). Here 

 and there more than two parasites had united, forming a stellate 

 group (Photo 12), and in one case I noticed that the individuals 

 had apparently united with their non-flagellated ends just overlap- 

 ping, so that the unstained spot in one was just situated in a line 

 with the unstained spot of the other (fig. 193). 



Fig. 193. 



" Surra" parasites occurring singly and fused. 

 From preparations stained with magenta x 1200. (Lent by Dr. Evans.) 



I have already mentioned that in Evans's Report Lewis's opinion 

 is given that these parasites differed slightly, but still were closely 

 allied to certain flagellated organisms which had been observed by 

 him in rats in India. On referring to his original memoir * I 

 found that his desertion and woodcut differed very materially 

 from the Surra parasite as just described, though a photomicrograph 

 which Lewis had appended to the memoir after it was written 

 indicated a great similarity to this organism. To me, the organisms 

 appeared not only closely allied, but as far as one can judge from 

 figures and descriptions, morphologically identical with the parasites 



* 'Microscopic Organisms in the Blood of Man and Animals,' Calcutta, 

 1879 (with photo); and Quart. Journ. Micr. Sci., lxxiii. (1879) pp. 109-14. 



