Ryder.] 120 [May 16> 



Clearly, then, the amount of chromatin in relation to the amount of 

 cytoplasm varies all the way from an almost inappreciable quantity in the 

 nucleus of the true egg to a very great quantity in proportion to the cyto- 

 plasm in the egg which produces a large quantity of chromatin from its 

 nucleus to provide the material for the nuclei of the multitudes of sper- 

 matozoa to which such an egg gives rise. 



Maleness, therefore, in the case of Ostrea edulis is certainly, and proba- 

 bly in all other forms, a condition where the chromatin preponderates 

 over the amount of cytoplasm, while, conversely, fenialeness is charac- 

 terized by the preponderance of cytoplasm over chromatin or nuclear 

 matter ; that is to say in the sexual elements only. 



Such a preponderance is not simply relative, it is absolute as respects 

 the one or the other of the primary germ-constituents. It is also a fact 

 that the amount of chromatin or nucleoplasm in an egg-nucleus, when 

 nearly mature, is in excess, as expressed in volumes, by at least four times 

 that of the chromatin contained in the mature male element of the same 

 species. Does this last fact signify anything in reference to the expulsion 

 of the polar bodies ? It probably does if the interpretation of the polar 

 bodies presently to be offered is true. And that that interpretation proba- 

 bly is true or more nearly true than any other yet offered, will become 

 clearer as we proceed, since it imports nothing into the discussion of the 

 data which is not in conformity with the facts of continuous growth or 

 which must be brought in in order to save previously suggested hypoth- 

 esis. It postulates only continuous growth under the condition of an ex- 

 cess of nutrition beyond that required in the secular exhibition of the 

 physiological activities of living forms. It supposes that this excess is 

 somehow influenced in one of two ways, that is, it is either preponderat- 

 ingly converted into chromatin or preponderatingly into cytoplasm. 



If mainly into cytoplasm, the process may go on until the cytoplasm 

 itself may tend to run down chemically into the more stable conditions of 

 oils, or yolk granules and tablets consisting of simpler molecular units. 

 This last process may go on until an enormous yolk is developed which 

 is composed of inert or immobile nutritive matters, while the active cyto- 

 plasm itself may become small in amount and reduced to a relatively small 

 volume. * Such a process never occurs in the male. Here karyoki- 

 netic processes keep the upper hand (not necessarily katabolic ones, or 

 those leading to destructive metabolism), and the result is that the male 

 element tends to be reduced in dimensions with no katabolically simpli- 

 fied contents, such as are met with in many eggs, but, on the contrary, con- 

 sisting mainly of plasma in a highly anabolic condition as chromatin. 



Plow these differences on the sexual elements are produced is not known, 

 but it is certain that they must be produced by the action of the physio- 



* This is so clearly in its general features a katabolic process, that it is impossible to 

 see how Geddes and Thomson can reconcile this with their hypothesis that the egg is 

 anabolic, while the male element is essentially katabolic ^see their work, "The Evolu- 

 tion of Sex," New York, 1890.) 



