No. I.] POLYCHOERUS CAUDATUS. 99 



the Other hand, the fact that the greater portion of these 

 clumps is dissolved when in the form of equatorial rays, might 

 be explained by supposing that the condensation of the already 

 formed chromosome particles drags with it granules of the less 

 differentiated, soluble chromatin which have in them nothing 

 which is to be transmitted to the next cell generation. This 

 theory in no way conflicts with the "reduction theory" or 

 with the existence and transmission of the "determinants," 

 " ids," etc., of Weismann. It simply asserts the existence of 

 two chromatic substances in the nucleus, which, though micro- 

 scopically indistinguishable, differ in the fact that the one 

 which is retained contains all that is essential to heredity, 

 while the other contains substances which are not to be 

 transmitted to the daughter nuclei, but become a part of the 

 cytoplasm. 



The absorption by the cytoplasm of some of the products of 

 the nucleus is not an uncommon phenomenon, and the connec- 

 tion between the nucleus and yolk nucleus (15) shows that 

 chromatin is not necessarily a substance transmittible to the 

 chromosomes alone. An objection to this theory is that it 

 assumes the existence of a force to hold together or to col- 

 lect the chromosome particles containing the " determinants " 

 and " ids " near the center of the nucleus. If the second prop- 

 osition is accepted, we must assume that the insoluble particles 

 received from the parent oogonia have degenerated, for they 

 were at one time insoluble ; if the third is accepted we must 

 assume that the greater portion of the hereditary qualities 

 existing in the nucleus are dissolved up as food for the cyto- 

 plasm. The supposition then that there are two kinds of 

 chromatin stuff, the one insoluble and bearing the heredity 

 which is to be transmitted to the daughter cells, and the 

 other food for the cytoplasm, seems unavoidable. 



The exact use of this food is of course pure conjecture, but 

 the following suggestion may be worthy of notice. When 

 the soluble chromatin is thrown out into the cytoplasm, it is 

 digested quite rapidly; and then, and not till then, do the cen- 

 trospheres (which up to this time have been very small) begin 

 to grow and attain their full size. May it not be that the 



