384 



TRYPANOSOMID^ 



In the Vertebrate. — If an uninfected or clean non-immune is in- 

 fected by the bites of infective invertebrates, at first no parasites 

 are to be found in the peripheral blood, and some days must elapse 

 before they appear. This interval is the incubation period. What 

 takes place during this period is but little known, the only observa- 

 tions being those by Fantham, who saw a few rounded forms fifteen 



Fig. 89. — Diagram aFTHE Life-Cycle of Trypanosoma lewisi Saville Kent, 

 1880, IN THE Body of the Rat. 



I, Trypanosoma lewisi; 2-10, stages in rosette formation; 11-13, develop 



ment of a small flagellate form into a trypanosome; 14, binary fission. 

 (Constructed from drawings by Moore, Breinl, and Hindle in the Annals of 

 Tropical Medicine and Parasitology.) 



to eighteen hours after inoculating T. castellanii and T. rhodesiense 

 into rats; and those by Franga, who reports the presence of similar 

 forms at a later stage of incubation . These are probably multiplica- 

 tion forms, which are the parent forms of the trypanosomes presently 

 to be seen in increasing numbers in the blood. 



