534 



GENERAL CONSIDERATION OF PROTOZOA 



expulsion of chromatin from the nucleus into the cytoplasm. The 

 cromidia, or idiochromidia, so formed collect in more or less well-defined 

 masses, and these are known as the secondary nuclei, which, however, 

 have no nuclear membranes, but consist simply of seggregated masses 

 of extranuclear chromatin. Two such masses fuse, and this is the 

 process of syngamic nuclear union, autogamy, or automyxis. It is a 

 self-fertilization and the most primitive type of sexual reproduction 



FIG. 182 



Amoeba limax. Chromidia forming from nucleus and collecting in the cytoplasm prior to 



encystment. (Calkins.) 



in protozoa. It occurs in many species of ameba, and has been 

 studied frequently in Amoeba limax. In Entamceba hystolytica, the 

 parasite causing amebic dysentery in man and monkeys, which is 

 not only prevalent in the tropics but also in the southern parts of 

 this country, and even sporadically in the Northern States, Schaudinn 

 and Craig have observed the formation of idiochromidial masses by a 

 fragmentation of the original nucleus. These masses become located 

 at the periphery, are provided with some cytoplasm from the surface 



FIG. 183 



Amoeba limax budding, division, and idiochromidia forming stages. (Calkins.) 



as buds, and are finally cut off. In this species of ameba, however, 

 the union of two masses of idiochromidia has not been actually 

 observed. Other species of ameba show a more complicated process 

 of chromidia formation and union (conjugation) between two masses 

 formed. In Amoeba proteus, Calkins has observed the following 

 process of autogamous reproduction. There is no formation of 

 diffused idiochromidia, but the secondary conjugating nuclei are 



