Ryder.] J-5u [M ay 16, 



traced to the secondary evolution of a cytoplasmic field, sexuality also 

 having so arisen at about the same time. The multicellular or coherent 

 condition produced new and more complex morphological relations lead- 

 ing to the manifold differentiation of physiological functions in relation 

 to diversification of surroundings, thus introducing a new and powerful 

 cause or capacity for variations and adaptations under such diverse condi- 

 tions. It is in the highest degree probable that the evolution of a cyto- 

 plasmic field and of sexuality, which depends upon the former, first ren- 

 dered variability possible. 



21. Cumulative integration in the vegetable led to the process of cumu- 

 lative integration in the animal world and to the overproduction of germs 

 or young in both of these kingdoms of life. The rate of increase thus 

 became augmented in a geometrical ratio, as supposed upon the Darwinian 

 hypothesis, which on the basis of the theory of the struggle for existence 

 and the process of natural selection so evoked, accounts for the preserva- 

 tion through survival and inheritance of valuable or advantageous varia- 

 tions which first arose as supposed above. Cumulative integration is 

 regarded as the primary cause of morphological differentiation under the 

 stress of diverse conditions, as well as of the geometrical ratio of increase 

 of individuals and consequently of the struggle for existence. The effects 

 of the struggle for existence have however been modified through the 

 already attained morphological differentiation of many forms in that the 

 nature of further possible modifications have been in some cases very 

 clearly determined by the character of those which have immediately 

 preceded the last modification. This principle of cumulative adjustment 

 through which superposition of adaptations occurs, is the law of cumula- 

 tive morphological differentiation. 



22. The only cells in multicellular forms which are absolutely otherwise 

 functionless are the germ cells. They alone, therefore, can become the 

 vehicles for the transmission of all the traits of the parent in higher forms. 

 They are the only cells of the body which, by any stretch of the imagina- 

 tion, can be supposed to possess the recapitulative power manifested in 

 ontogeny. 



23. In that the germinal cells are never belabored with any physiologi- 

 cal function in the parent body, except cumulative integration, they are 

 also the only ones which lead the charmed life of a perpetual youth. 

 Upon this peculiarity of germ-cells depends rejuvenescence through re- 

 production, and the maintenance of the maximum vigor of the species. 



24. In that maximum vigor of growth concentrated upon apical or 

 nearly acropetal cells in plants determines their sex, and in that this seems 

 to hold in great measure in Algre and Fungi, and in that the gradually 

 deeper inclusion of germ-cells and germ-tracts in animals is clearly a con- 

 sequence partly of further morphological development, as well as of the 

 effect of the repulsion of the functionless germ-cells into positions where 



