REPRODUCTION 



some of the older writers, but even some recent ones, 

 regard sexual generation as a universal function of or- 

 ganisms, and declare that it dates from the very begin- 

 ning of organic life. 



The complex and frequently very intricate phenomena: 

 of sexual generation, as we find them in the higher organ- 

 isms, become intelligible to us when we compare them 

 with the simpler forms of asexual generation at the low- 

 est stages of life. We then learn that they are by no 

 means unintelligible and supernatural marvels, but nat- 

 ural physiological processes, which, like all others, may 

 be traced to the action of simple physical forces. The 

 form of energy which lies at the root of all tocogony is 

 growth (crescentia). And as this phenomenion is also 

 the cause, in the form of gravitation, of the formation of 

 crystals and other inorganic individuals, we do away 

 with another of the boundaries which people would es- 

 tablish between organic and inorganic nature. Repro- 

 duction is a kind of nutrition and growth of the organ- 

 ism beyond the individual standard, building up a part 

 of it into a whole. This limit of individual size is deter- 

 mined for each species by two factors — the inner con- 

 stitution of the plasm, which is inherited, and the de- 

 pendence on the outer environment, which controls 

 adaptation. When this limit has been passed.the trans- 

 gressive growth takes the form of reproduction. Every 

 species of crystal has also a definite limit of growth; 

 when this is passed, new crystal-individuals are formed 

 in the mother- water on the old individual, which grows 

 no further. 



Asexual or monogenetic tocogony (also called " vegeta- 

 tive multiplication") is always efiEected by a single or- 

 ganic individual, and so must be traced to its transgres- 

 sive growth. When this affects the entire body as a 

 total growth, the whole dividing into two or more equal 

 parts, we call the monogenetic process division (or seg- 

 i6 241 



