ONTOGENESIS 185 



forms, and as a consequence we find them the domi- 

 nant type to-day. 



MORPHOGENESIS 



The goal of the reproductive process is the forma- 

 tion of a new individual. In asexual reproduction, 

 particularly by budding, it is often a matter of great 

 difficulty, and, perhaps, of minor importance, to 

 determine where the limits of individuality lie. 

 In those forms which develop sexually, the individual 

 comes into existence with the fusion of the gametes 

 (or of their nuclei) to form the zygote. In other 

 words, the zygote is the new individual, however 

 little it may resemble what we are accustomed to 

 call the specific type. Before it can reproduce a 

 second generation, however, it must be transformed 

 into that type. This it does by a series of remark- 

 able changes (see page 158 ff.) accompanied by 

 growth, to which the name Morphogenesis is given. 



Regeneration. The phenomenon of morpho- 

 genesis is not only discoverable in the acquisition 

 of the specific form, that is, in development, but also 

 in the restitution of that form when it is altered or 

 destroyed. Thus, if one cuts off the leg of a sala- 

 mander or of a crayfish, a new growth of tissue will 

 take place at the cut surface, and this new tissue 

 will differentiate into a new leg which is the du- 

 plicate of the one destroyed, or, if not the exact 

 duplicate, at least conforms exactly to the specific 

 type. This function of the organism is known as 

 regeneration. It is not found in all organisms, but 



