MORE COMPLICATED LIFE CYCLES 



121 



such condensation, hut the idiochromidia granules collect in a loose 

 shell or rind about the karyosome, and from it granules of chromatin 

 are discharged into the surrounding protoplasm prior to encystment 

 (Fig. 50). During encystment these distributed granules are abun- 

 dant in the cell while the karyosome becomes indistinct and ultimately 

 degenerates. Under proper environmental conditions (which may be 

 brought about artificially by changes in temperature) the idiochromidia 

 fuse into sixteen groups of secondary nuclei (Fig. 51). A similar 

 method of idiochromatin formation was described by Schaudinn 

 ('03), and more recently by Craig ('OS), in the case of Entameba 

 histolytica. 



Not only idiochromidia, but chromidia as well, may be formed by 

 this method of nuclear dissolution. Thus, in some coccidia and grega- 

 rines according to the observations of Siedlecki ('07) and Leger ('07), 

 on caryotropha and ophryocystis, respectively, a similar disposal of 

 the peripheral rind of chromatin gives rise to degenerating granules 

 which, possibly, according to both observers, may have some vegeta- 



FiG. 50 



Aineba limax. Chromidia forming from nucleus and collecting in the cytoplasm 



prior to encystment. 



tive function in cell metabolism. The latter, therefore, apparently 

 agree with Hertwig's chromidia in actinospherium. 



Nuclear Fragmodation. — Idiochromidia formation by fragmenta- 

 tion is widely scattered among protozoa, and has been described by 

 numerous observers, first by Schaudinn ('94), and by many others 

 since, in connection with various forms of foraminifera, rhizopods, 

 flagellates, and sporozoa. The most widely recognized example of this 

 mode of idiochromidia formation is the case of Polystomella cri.spa, 

 one of the foraminifera. Here, according to the independent obser- 

 vations of Schaudinn ('03) and Lister ('05), the nuclei of the micro- 

 spherical generation increase by division until a large number are 

 formed. The older ones then disintegrate, or fniguKMit, into minute 

 chromatin granules, which are ultimately tlistributed throughout the 

 protoplasm. Later aggregations of these idiochromidial granules give 

 rise to the nuclei of the conjugating gametes (Fig. 52). Similarly in 

 the coccidian Klossia octnpiana, according to the researches of Siedlecki 

 the nuclei of the microgainotes, and in Grccjarina cuncata, according 



