REPRODUCTION 



239 



are wriggling very actively; the envelope becomes more and more 

 tense, and finally bursts with explosive suddenness, setting free 

 the flagellates, usually about eight in number, within the host cell 

 (Fig. 118, 12). The products of this method of multiplication are 

 full-sized trypanosomes, complete in their structure, and differing 



Fig. 119. — PolystomcUa crispa. A, zygote, {A) develops into an organism with a 

 microsphseric type of shell {B) in which the nucleus divides by mitosis until many 

 nuclei are present which form chromidia. The protoplasm fragments into reproduc- 

 tive bodies or agametes, each having several granules of chromidia (C) . Each agamete 

 develops into an adult with a macrosphieric-type of shell (D.E.): when adult these 

 fragment into hundreds of flagellated gametes (F) which fuse in fertilization and so 

 complete the cycle. (From Lang and Schaudinn.) 



but slightly in their characters from those found in the blood of the 

 rat. They escape from the host-cell into the lumen of the stomach." 

 (loc. cit. p. 299). 



Similar multiple division phases have been described for Trypano- 

 soma cruzi (Chagas, Hartmann), for Eutrichomastix serpentis, and 

 Tetratrichomonas prowazeki (Kofoid and Swezy), Lophomonas blattcB 



