1890.] [Ryder. 



the cytoplasm or cytoplasm and yolk of the hypertrophied female sper- 

 matogonium or ovum, it must have access to the latter. 



The egg before the expulsion of the polar bodies is a spermatogonium, 

 after that and exclusive of the polar bodies it is the exact homologue of 

 the spermatozoon in that its nucleoplasm is now reduced to the volume of 

 the nucleoplasm of the male element of the same species. 



The male spore is however so specialized as an organism in nearly all 

 forms that it is incapable of nourishing itself. Clearly, the only way it can 

 do so is to find lodgment in a body whose molecular constitution is as 

 nearly as possible similar to itself, otherwise its identity must perish in 

 that it would either be digested or in some way absorbed, neither of which 

 fates befall it in the egg, as we know from observation. That body in 

 which it can find lodgment is the female spore or germ of its own species, 

 in which it is not only not digested but is taken in as a partner literally, 

 since it completely fuses with the female centre of control hitherto coor- 

 dinating and maintaining the integrity of the cytoplasm. 



But as soon as this fusion of the starved spore male element and the 

 overgrown female element happens, the further changes which now take 

 place must proceed in the presence of the stimulus of abundant nutriment 

 (represented by the cytoplasm of the egg) for the male ; but this is not 

 all, the egg is now detached and cannot be nourished for a time, and its 

 career of development is now also profoundly influenced by such all im- 

 portant new conditions as the surrounding oxygen affords for renewed 

 metabolism, under the new free condition, all of which taken together 

 makes for a tendency towards a new mode segmentation which tends to 

 recapitulate the growth of the parent form. 



The process of fertilization is probably more like one in which there is 

 a reciprocal blending of two living bodies in which there is no loss of 

 identity of either in that their essential molecular constitution is exceed- 

 ingly similar. Reciprocal digestion does not occur since the organization 

 of both germs would be sacrificed if such a process were to occur. So far 

 from that the organization of both germs is in a sense maintained, and we 

 have in the blending of male and female elements the paradox of two 

 cells becoming one without the sacrifice of organization in either during 

 the process of fusion. It is therefore manifest that the application of the 

 term mutual or reciprocal digestion as attempted by Rolph and maintained 

 by Geddes is wide of the mark and not descriptive of the process at all. 

 " Fertilization " is really the highest and most specialized form of molecular 

 integration, and is itself the highest phase, and a consequence of the uni- 

 versal principle of cumulative integration, which underlies all continuous 

 growth which in turn must end, on account of the requirements demanded 

 by the surroundings, in discontinuous growth, the production of unlike 

 germs by the same species, and consequently in sexuality.* 



* The theory of the polar bodies developed in this paper remains to be put to the test. 

 I find that the nuclei of the spermatozoa of Ostrea edulis take up the methyl green while 

 the nuclei of the spermatogoaia take up the saffranin from a solution of those two dyes 



