TRYPANOSOMES OF AMPHIBIA 597 



Morphology. — The first trypanosomes to appear in a frog after inocula- 

 tion are small trypanosomes with a body 16-5 to 21 microns in length by 

 1-5 to 2-2 microns in breadth. The posterior end of the body is pointed, 

 while the margin of the undulating membrane is fairly straight. The 

 flagellum is 6 to 10-5 microns in length. The nucleus is central and the 

 kinetoplast well developed. These are the forms seen by the original 

 observers, who noted that the trypanosome bore a striking resemblance to 

 the late phase form of T. leivisi of the rat (Fig. 241, 4-6). After a few 

 days, during which the small forms alone are present in the blood, larger 

 forms begin to appear by growth of these. They measure 35 to 36 microns 

 in length and 2-2 to 3-5 microns in wddth. These are the trypanosomes 

 which were originally described as T. elegans (Fig. 241, 2-3). The flagellum 

 is only 5 to 6 microns in length. By continued growth they give rise 

 to still larger forms (T. undulans) 36 to 37 microns by 4-5 microns 

 (Fig. 241, i). Sometimes much larger forms up to 54 microns in length 

 occur. About a month after the infection first appeared the large forms 

 may be the only ones present in the blood. 



Apparently none of these various types of trypanosome seen in the 

 blood is undergoing division. Fran9a (1915), in smears of the lung, has noted 

 within the cells leishmania forms, many of which are in process of division. 

 Between these and the small trypanosomes every intermediate stage can 

 be traced. It would thus appear that reproduction takes place by division 

 of leishmania forms in the lung or other organs in much the same way as 

 occurs in T. cruzi. The leishmania forms are apparently derived in the 

 first place from the flagellates inoculated by the leech. 



Transmission. — Billet (1904), who found a variety of flagellates in the 

 intestine of the leech {Helobdella algira), which fed upon the frog, came to 

 the conclusion that it was the transmitting host of the trypanosome 

 (Fig. 242). Accordingly, Brumpt (1906c) in Paris obtained a number of 

 these leeches from Algiers. He found that Rana esculenta of France was 

 easily infected by the bites of the leeches, the first trypanosomes appearing 

 in their blood in eight to ten days. The European frog, moreover, was 

 very susceptible, for in many cases the infection proved fatal. The 

 trypanosomes were found to be present in enormous numbers, the heart 

 of frogs which had died being filled with an embolus of the organisms. 

 R. temporaria is also susceptible to the infection. Franca (1915, 1920) 

 notes that the heaviest infections follow inoculation with the young 

 forms of the trypanosome. 



The process of development in the leech has been described by Brumpt 

 (1906c). The large form of the trypanosome is the one taken up by the 

 leech, and in the stomach it gives rise to numbers of crithidia forms. 

 This process does not seem to have been described in detail, but from 



