20 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



forms ; that is to say, they consist of simpler parts 

 of different characters, which have a special arrange- 

 ment with regard to one another ; these parts have a 

 typical form of their own and may again be combina- 

 tions of more simple different parts. But besides that, 

 living bodies have not always the same typically com- 

 bined form during the whole of their life : they become 

 more complicated as they grow older ; they all begin from 

 one starting point, which has little form at all, viz., the 

 egg. So the living form may be called a " genetic form," or 

 a form considered as a process, and therefore morphogenesis 

 is the proper and adequate term for the science which deals 

 with the laws of organic forms in general ; or, if you prefer 

 not to use the same word both for a science and for the 

 subjects of that science, the physiology of morphogenesis. 



Now there are different branches of the physiology of 

 morphogenesis or physiology of form. We may study, and 

 indeed we at first shall study, what are the laws of the 

 morphogenetic processes leading from the egg to the adult : 

 that may be properly called physiology of development. But 

 living forms are not only able to originate in one unchange- 

 able way : they may restore themselves, if disturbed, and 

 thus we get the physiology of restoration or restitution as a 

 second branch of the science of morphogenesis. We shall 

 draw very important data, some of the foundations indeed 

 of our philosophical discussions, from the study of such 

 restitutions. Besides that, it is to them that our survey of the 

 problems of the physiology of metabolism is to be appended. 



Living forms not only originate from the egg and are 

 able to restore themselves, they also may give origin to 

 other forms, guaranteeing in this way the continuity of life.. 



