598 



FAMILY: TRYPANOSOMIDiE 



observations under the cover-glass in wet films Franca has noted that the 

 large trypanosomes became more rounded and that multiplication of the 

 nuclei and kinetoplasts takes place till several pairs are present. The 

 cytoplasm segments into a corresponding number of crithidia forms after 

 axonemes have grown out from the kinetoplasts. It is probable also that 

 the large forms divide unequally and repeatedly, giving rise to small 

 crithidia forms with gradual reduction in size of the parent. In whatever 

 manner the process takes place in the leech, the stomach soon becomes 

 crowded with large numbers of these crithidia forms, which multiply by 



fission in the usual manner. Eventually a 

 return to the trypanosome type is noted, 

 and it is these forms which probably, by 

 migration along the oesophagus to the open- 

 ing of the proboscis, gain access to the 

 cavity of the proboscis sheath, w^here they 

 accumulate, and are transmitted to the 

 frog when the leech feeds. In the case of 

 this trypanosome of the frog, as with the 

 others which have been considered above, 

 the trypanosomes taken up by the inver- 

 tebrate become at first crithidia forms, 

 which later are transformed into try- 

 panosomes again. These metacyclic try- 

 panosomes which appear at the end of 

 the cycle reproduce the infection in the 

 vertebrate. 



In connection with the transmission of 

 T. inopinatum by the leech, H. algira, 

 Brumpt (1907) noted what is interpreted 

 as a definite hereditary transmission in the 

 leech. The embryos, when they hatch from 

 the egg, attach themselves to the ventral 

 surface of the parent leech, and in this position were found by Brumpt 

 to be infected. He has been able to observe this infection persisting 

 through five successive generations of leeches. The infected young are 

 able to infect frogs. Brumpt considers that the egg is infected while still 

 within the parent, but he does not seem to have excluded the possibility of 

 the young leeches being infected soon after hatching from flagellates which 

 escape into the water from the intestine of the parent. He does not state 

 whether young leeches removed from the egg are already infected or not. 

 Culture.— Ponselle (1923) has shown that T. inopinatum is readily 

 culturable in a mixture of equal parts of defibrinated rabbit's blood 



Fig. 242. — Helohdella algira 

 (x5), THE Transmitter of 

 Trypanosoma inopinatum. 

 (After Brumpt, 1922.) 



Dorsal view and ventral view with 

 attached eggs. 



