5U 



Dr. C. Morley Wenyon 



[March 3, 



the opportunity of indulging in a feed of blood while the rat is off 

 its guard. The white fur will become bespattered with droplets of 

 blood ejected by the fleas. The rat, suddenly aroused from its torpor, 

 turns its head round to alleviate the irritation by licking the spot, in 

 doing which it laps up the blood which the fleas have deposited. 



A _/^i 



TO 



s. 



f*f 



Fig. 6. — The Teypanosome {Trypanosoma lewisi) op the Rat, and its 



DEVELOPMENT IN THE FLEA. 



A Trypanosomes in the blood of the rat. (Magnified 1500 times.) 

 b-s Diagram of the development in the flea. 

 S, trypanosomes in the stomach ; r, trypanosomes in the rectum which are 

 deposited on the skin in the droplets of blood ejected by the flea. 



b, c, d Details of development in the flea. (Magnified 1500 times.) 

 b, multiplying trypanosome in one of the cells lining the stomach of the flea ; 

 c, developmental forms attached to the cells lining the rectum of the 

 flea; d, trypanosome forms which are voided in the dejecta of the flea 

 and which are eaten by the rat and cause its infection. 



