252 University of California Publications in Zoology [Vol. 19 



as related in some way to this kinetic membrane, either in origin or in 

 underlying causes. 



The substance of the microkaryosome is quantitatively smaller than 

 the chromatin of the metaphase chromosomes (equatorial plate). 

 These latter seem undoubtedly to be derived from both peripheral and 

 karyosome chromatin. The most probable way in which peripheral 

 chromatin can get upon the skein or into the metabolic membrane, is 

 by entering into solution and being again deposited on the inner 

 achromatic framework, within the membrane. This would eliminate 

 any interpretation of the continuity of all of the substance of chromo- 

 somes in Collodictyon. Much has been written of late concerning the 

 individuality of chromosomes and this is regarded by many as funda- 

 mental to any mechanism of Mendelian inheritance, especially as 

 interpreted by Jannsen and Morgan in their "chiasma-type theory" or 

 "theory of crossing over." Wenrich (1916) presents probably the 

 best morphological evidence of the continuity of the chromosomes, so 

 far recorded. He, however, does not claim to present observable proof 

 of such continuity, but finds in his observations and correlations, 

 together with reasonable conclusions from hybridization and other 

 experiments, that the evidence is greatly in favor of such continuity. 

 Moenkhaus' (1904) conclusion from his hybridization experiments is 

 typical: "If from such a nucleus, two kinds of chromosomes again 

 emerge, it amounts almost to a demonstration that the chromatin 

 substance of a given chromosome forms a unit and that unit persists." 



In Collodictyon the chromatin cycle consists of an apparently 

 homogeneous karyosome, separation and possible elimination of major 

 part, an apparent solution phase, prophase segmented spireme with 

 terminal knobs, metaphase chromosomes, anaphase synizesis and 

 growth, followed by a typical spireme of small nodular granules, 

 which later unite into irregular masses, from which the daughter 

 karyosome is reorganized. 



Inheritance in Binary Fission 



In sexual plants and animals the hereditary substance can be 

 localized in the germ cells, though all reproduction is not by means 

 of such germ plasm. In flagellates, reproducing alone by the method 

 of simple binary fission, and in which sex is unknown, the problem of 

 heredity becomes more complex, instead of simpler of analysis. 



Were the problem solved for higher organisms, those conclusions 



