600 APPENDICES. 



distinct generic and family group for the reception of these singular 

 organisms." In his later paper, however, Lewis came to the con- 

 •clusion that, like the generality of flagellated organisms, the rat 

 parasites moved with the lash in front. 



On careful examination the plasma which constituted the thicker 

 portion of their substance was observed to suddenly swell out so as 

 to divide the body into two parts, as seen in the centre of the figure ; 

 &t other times two or three such constrictions or dilatations were 

 detected, and at other times the body assumed an arrow shape, as 

 depicted at the lower part of the figure. When dried, and stained 

 with a little weak solution of aniline-blue, the body presented a very 

 difierent appearance. It was found to have contracted ii'regularly, 

 and to manifest a somewhat granular and shreddy appearance, 

 suggestive of a coagulated fibro-albuminous substance. The body 

 portion became flattened towards its middle to double its original 

 width, and both ends almost acutely pointed, while the flagellum 

 was only partly visible. After fixing with osmic acid they measured 

 O'S to 1 /A in width, and 20 to 30 /x in length ; the flagellum was about 

 as long as the body : so that the total length of the organism was 

 xibout 50 fn. Lewis detected these parasites in 29 per cent, of the 

 species Mus decumanus and Mus rufescens, but failed to find them 

 in mice. He considered that they had many features in common 

 with motile organisms of vegetable origin ; but they appeared , to 

 approach much more closely to the Protozoa, more particularly 

 several of the species of Dujardin's Oercomonas. He points out 

 that many, however, believe that these organisms are zoospores and 

 not animalcules. To him they also seemed to be not unlike the 

 flagellated parasite described by BUtschU. 



The latter observer detected flagellated organisms (Leptomonas 

 Biitschlii) in the intestinal canal of a free nematode (Trilobus 

 gracilis). They, too, form stellate colonies, like the Surra parasite, 

 ■owing to their being attached by their nor(-flagellated ends. When 

 detached from these colonies they presented a somewhat spindle- 

 shaped body about 1 1 /^ in length, with a somewhat thick flagellum 

 about double this length, so that the total length of the protozoon 

 would be 33 /j., or, as Lewis states, about half the length of the 

 flagellated organism in the rat's blood. Near the base of the 

 flagellum, Biitschli's protozoon presented a contractile vacuole, 

 but Lewis was unable to detect any such vacuole in the rat 

 iiematozoa. 



In conclusion, Lewis observed that very probably these organ- 

 isms corresponded with 'the vermicnles observed by Goss in the 



