1890.] 139 (Ryder. 



cules in that here the molecular differences are zero or nearly so, and at 

 most goes no further than molecular differences, having their origin in 

 the individual traits of either of the two parents. The last or sexual 

 form of integration or intussusception also occurs, en masse, and without 

 any reciprocal sacrifice of molecular identity. This last form of organic 

 molecular integration is therefore effected with the least expenditure of 

 energy on the part of the sexual elements themselves which are involved. 

 Sexuality according to this view as expressed primarily in conjugation is 

 a sort of refined hunger, in which neither the "eating " nor the " eaten " 

 expends but a minimum of energy in a process of reciprocal assimilation. 

 It is a hunger in which the sense of "taste" in the vulgar, anthropo- 

 morphic sense is unknown ; it is an affinity developed possibly through 

 the attraction of identical molecular aggregates for each other. 



The principle of cumulative molecular integration is similar in some 

 respects to the cumulative principle operative in organic structural evolu- 

 tion, through which a superposition of adaptations results, not necessarily 

 as the consequence of selection but as the result of the morphological and 

 physiological necessity of conforming in the next step of morphological 

 and physiological complication to that which had preceded it. Many in- 

 stances in illustration might be cited, such as the annular placenta of the 

 ovum necessarily conforming to the easiest possibility of internal contact 

 with a tubular uterine canal. This principle has been responsible for 

 much that has happened in organic evolution, but it is again dependent 

 in curious, circuitous ways upon the still more primary principle of cumu- 

 lative integration, overgrowth of organisms, or their capacity to grow be- 

 yond their own bulk at certain points, as implied by Haeckel. 



The highest form of cumulative integration ending in an overgrown and 

 abortive spermatogonium, which is the equivalent of the egg, together 

 with its further expression in the production of spermatozoa which have 

 had their cytoplasmic field reduced, leads to a condition where the one 

 becomes helpless without the other. It also presumably leads to the evo- 

 lution of an appetency or affinity of the male for the female element in 

 that the one possesses what the other does not, and in that they are pro- 

 duced in similar organisms or those of the same species their idioplasrnic 

 constitution must be very nearly the same, except for the morphological 

 differences which characterize them. These differences are again the pre- 

 ponderance of nucleoplasm in the one or the element immediately con- 

 cerned in growth and the physiological integrity of the living cell, and 

 the preponderance of cytoplasm in the other, which* is the medium in 

 which free nuclear motion, karyokinesis, and consequent growth is possi- 

 ble. The affinity so developed through cumulative integration by the 

 divergent processes of ovogenesis and sperniatogenesis ends in what I 

 shall term reciprocal integration without loss of molecular identity, or in 

 what is usually termed " fertilization." 



The advantages offered by such a process is that it provides for the de- 

 velopment of metazoan or multicellular embryo, which is without the 



