PROWAZEKIA ASIATIC A 



341 



containing food vacuoles, but no contractile vacuole. The tropho- 

 nucleus is usually situate in the flagellar third of the cytoplasm, 

 and consists of a nuclear membrane, a widish space for the enchylema, 

 and a central karyosome, with usually a centrosome. The kineto- 

 nucleus is situate nearer the flagellar 

 extremity, and is connected by a long 

 strand with a small piece of chromatin 

 situate near the aflagellar extremity, and 

 by another strand with one of the two 

 blepharoplasts which lie adjacent to the 

 flagellar extremity. These blepharo- 

 plasts are united together, and, as already ■" " - . . 

 stated, to the kinetonucleus by strands. "i^^jiiryr 

 Usually there are two, which may lie w 

 side by side or one over the other. From 

 these blepharoplasts the two flagella take - 

 origin, and quickly pass to the exterior. 



Reproduction. — Asexual reproduction 

 takes place by metamitosis, but sexual 

 reproduction is unknown. Cyst formation 



has been observed, resulting in rounded pi^. eg.—Prowazekia asi- 

 bodies 6 to 7 in transverse diameter, atica Castellani and 

 possessing tropho- and kineto-nuclei, and Chalmers : From F^ces. 

 enclosing the remains of the flagella. 



Culture. — P. asiatica is readily cultivated in liquid and in the 

 water of condensation of solid media in symbiosis with bacteria. 

 The most suitable medium is the condensation water of nutrose 

 agar (2 to 4 per cent.), or maltose agar, on which a few drops of 



Fig. 70. — Prowazekia asiatica Castellani and Chalmers: From Cultures, 



(After Whitmore.) 



albumin-water have been placed, when it can be subcultured and 

 grown indefinitely if the tubes are kept uncapped and subcultures 

 are made twice a week. 

 Pathogenicity. — -Probably nil. 



