106 PARASITIC AMCEB^E OF MAN. 



and a complete dissolution of the nuclei takes place." 



After the reconstruction of the daughter nuclei 

 they are situated at opposite poles of the cyst and the 

 following changes may then be observed: 



Both divide by primitive mitosis so that two nuclei 

 lie at the opposite poles. One of these contracts, 

 forming a reduction body, while the other again 

 divides. This results in the presence of three nuclei at 

 each pole, two of them normal in appearance, while 

 one is degenerating. One of the newly formed nuclei 

 also degenerates eventually, leaving two nuclei at 

 each pole of the cyst. 



After this has occurred, the body of the amoeba 

 contracts still further and the cystic membrane be- 

 comes more pronounced, appearing firmer and more 

 refractile* The division between the two portions of 

 cytoplasm is lost, the two pair of nuclei divide mitot- 

 ically, two daughter nuclei being formed, called the 

 active and passive pronuclei. These pronuclei fuse, 

 forming two synkarya, each of which divides into four, 

 so that the cyst now contains eight daughter nuclei. 

 During this time the walls of the cyst have become 

 firmer and thicker and there is no indication of 

 division of the cytoplasm. Under favorable condi- 

 tions, such as reception into a new host, the cyst wall 

 dissolves, the cytoplasm divides into eight irregular 

 masses each containing a daughter nucleus, and in 



