WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 113 



believe we may therefore regard them as being related to the organiza- 

 tion of the chromosomes, just as much as the polar granules are. A 

 glance at the literature will show how constantly these structures are 

 found; but no one, except Miss Carothers, so far as I am aware, has 

 suggested that they are always attached to some definite region of a 

 chromosome. It would seem to be worth while for some one to make 

 a study of these structures from this point of view. 



The changes in staining capacity which the plasmosomes undergo 

 at different stages raises an interesting question as to what may be 

 their relation to the chromatin of the thread with which they are 

 associated. Do they take up chromatin from the chromatin-thread, 

 thus increasing their own stainability, and give it back again as they 

 lose their power to hold the stain? Do they elaborate chromatin 

 from raw materials in the surrounding cell substance and give it up to 

 the chromatin-thread? Is their chromatic substance different from 

 other chromatin? Or, do they have some other way of becoming for 

 a time chromatic and later non-chromatic? May it not be possible 

 to answer some of these questions by carefully resolving into its 

 chromomeres the chromatin-thread with which they are associated, 

 and comparing the constitution at different stages? I believe this 

 could be done on favorable material. In Phrynotettix, these struc- 

 tures are definitely related to polar granules. Are the polar granules 

 to be classed in the same category as the plasmosomes? Is it possible 

 for a polar granule to become transformed into a plasmosome, and then 

 back into a polar granule again? The last question seems to be an- 

 swered in the affirmative by the conditions in Phrynotettix. In the 

 case of B, for example, one of the proximal granules becomes "ex- 

 panded" in only about 16% of the cases counted. In becoming 

 expanded it has become like a plasmosome. When it is not expanded, 

 it remains a polar granule. Is it any wonder, then, that the plasmo- 

 somes have been called 'variable' and 'uncertain' elements of the 

 nucleus? 



Plasmosomes are associated with heterochromosomes, as well as 

 with autosomes. Davis ('08), for example, noticed one on the mono- 

 some of Stenobothrus, and I have confirmed the observation from 

 slides of my own. Morse ('09) found in cockroaches a plasmosome 

 constantly associated with the "chromatin nucleolus" (accessory), 

 and in addition another body in the cytoplasm, which he called a 

 plasmosome. A similar cytoplasmic body, which stains like chroma- 

 tin, is found in a number of Acrididae. Dederer ('07) found a plasmo- 

 some associated with the pair of idiochromosomes in Philosamia, and 



