386 



TR YPA NOSOMIDM 



which divides transversely, and each half goes to an opposite pole, 

 or the chromatin gathers around opposite poles. 



8. The connecting line disappears and two new trophonuclei are 

 formed. 



Rosette Formation. — -The medium-sized parasite, according to 

 Moore, Breinl, and Hindle, grows into large forms, which pass through 

 the following development : — ■ 



1. The trophonucleus undergoes reduction by amitosis, the re- 

 duction body disappearing. 



2. The kinetonucleus gives off a body, which travels — increasing 

 in size as it proceeds — to the trophonucleus, with which it perhaps 

 fuses, but this is not definitely known. 



In T. castellanii a strand forms between the kineto- and tropho- 

 nuclei, instead of this travelling body, which is seen in T. lewisi 

 and T. equip erdum. 



^3 ^ s 



Fig. 90. — Crithidia melophagia Flu. 

 (After Flu.) 



I, Microgamete; 2, macrogamete; 3. zygosis; 4, ookinete and degenerating 

 micro gamete; 5-8, ookinete in the alimentary canal and ovary. 



3. The tropho- and kineto-nuclei divide to form fusion masses con- 

 sisting of two, four, seven, or more small parasites, which at first 

 possess only the old fiagellum, but in which later new flagella form 

 (the rosette formation). This stage is not definitely known in 

 T. castellanii, 



4. The small parasites, which must be looked upon as representing 

 latent phases, separate from the fusion mass. These small parasites 

 grow mto medium-sized parasites, thus completing the cycle. 



All observers are agreed as to the rosette formation, and with 

 regard to the process from the kinetonucleus, this was first pointed 

 out by Miss Robertson, whose work is therefore confirmed. The 

 band is said to be composed of volutine. As to the latent phases, 

 we believe that they are the same as the peculiar aflagellate round 

 and oval forms described several years ago by Castellani, in the 

 cerebro-spinal fluid of sleeping-sickness patients, and which he com- 

 pared to the amoeboid forms found by Plimmer in the brains of 

 animals infected with nagana. 



