CYSTS OF DYSENTERIC AMCEB^E 157 



one of the present authors has done much work, has 

 a trophozoite from 20 to 30 /* in diameter, and 

 it possesses both ectoplasm and endoplasm. The 

 endoplasm is not intensely granular, but has the 

 power of feeding upon red blood-corpuscles. The 

 nucleus is large, round and possesses a karyosome, in 

 which a central spot is seen sometimes (Fig. 32, 6). 

 The multiplication is by binary fission and also by 

 schizogony. Some of the 

 smaller amoebae become 

 four-nucleate by division, 

 and each of these ultimately 

 divides into four mero- 

 zoites, which become sepa- 

 rate small amcebse. After 

 a number of asexual gene- 

 rations, cyst formation 

 commences. The amceba FIQ 34 _ Cysi QF ENIAM(EBA 



about to encyst Withdraws HISTOLYTICA, SHOWING THE 



its pseudopodia, becomes i^^," F RM WIIH 

 rounded, and ejects most 



waste products from its endoplasm. Nuclear changes 

 follow this rounding, and division into two occurs. 

 The division is repeated and a cyst with four nuclei 

 is produced (Fig. 34). Each nucleus collects cyto- 

 plasm and ultimately four spores are formed. These 

 cysts and spores are capable of producing heavy 

 infection if swallowed by a new host. 



Sometimes diseased or pathological specimens of 

 the amceba itself can be found. These forms show 

 abundant budding such as Schaudinn described for 

 the spore formation of Entamaba histolytica. They 



