546 



BIOLOGY OF THE PROTOZOA 



(1903) and confirmed in essence by Wenyon (1907) in Endamceba 

 muris (Fig. 228). The organisms encyst after a period in the host's 

 intestine; the nucleus of the encysted cell divides {A, B, C,) and 

 the cell body indicates an attempt to divide into two parts. The 

 protoplasmic connections between these tw^o cytoplasmic parts 

 are never lost so that subsequent processes take place in a binu- 



A / 





Fig. 228. — Endamceba muris. A, ordinary individual prior to encystment, in 

 division. B, an autogamous cyst; C, division of nucleus and vacuolization of cell; 

 these nuclei then break up into chromidia; E, reformation of two nuclei from chrom- 

 idia; F, G, two nuclei and so-called reduction bodies remain in the cyst, the former 

 now divide (G) to form 4 nuclei which unite 2 and 2 ; these nuclei now divide to form 

 4 and the 4 give rise to 8 (J). (After Wenyon.) 



cleated cell. The nuclei next fragment, forming idiochromidia 

 from which two smaller nuclei {D, E) are formed by segregation of 

 the scattered granules. Each nucleus then divides twice, one-half 

 at each division forming nuclei which degenerate in the cell (''reduc- 

 tion" nuclei). The other halves form two fertilization nuclei each 

 of which divides again, this time with the long axes of the spindles 



