THEORY OF REPRODUCTION. 



219 



a direct influence; in both cases, reproduction is the expression of a 

 katabolic crisis. 



VII. Conclusion. — Primitively, then, reproduction was a kata- 

 bolic rupture of a mass of protoplasm. This becomes more definite 

 in cell-division of various kinds, tending ever to occur at the limit of 

 growth when waste has made up on repair, or in katabolic conditions 

 due to the environment. In multicellular animals, anabolic conditions 

 favor overgrowth: a check to this brings about discontinuous asexual 

 reproduction. With increasing differentiation, the asexual multipli- 

 cation is replaced by the liberation of special sex-cells, by which the 

 life-saving and life-continuing sacrifice is rendered less costly. Just 

 as asexual reproduction occurs at the limit of growth, so a check to 

 the asexual process is often seen to involve the appearance of the 

 sexual, which is thus still further associated with katabolic preponder- 

 ance. This is confirmed by the contrast observed in alternation of 

 generations, where the two processes in varying degrees of distinctness 

 persist in the life-history of the same organism. Corroboration is 

 again afforded by the association of sexual reproduction with sundry 

 environmental checks of a katabolic character. And thus the oppo- 

 sition between nutrition, which, after life and death, is the most 

 obvious antithesis in Nature, admits of being more precisely restated 

 in the thesis, that as a continued surplus of anabolism involves growth, 

 so a relative preponderance of katabolism necessitates reproduction. 

 Or this may be summed up once more in our fundamental dia- 

 grams : — 



SUM OF FUNCTIONS. 



Nutrition Reproduction. 



A A 



Anabolism. Katabolism. Female. Male. 



Fig. 84. 



