THE WONDERS OF LIFE 



the reptiles and amphibia, and these in turn from those 

 of the fishes and the lowest vertebrates. Finally, the 

 phylogeny of the vertebrates proves that this highly 

 developed stem has advanced through a long series of 

 invertebrate ancestors (chordonia, vermalia, gastraeada) 

 from the protists by a process of gradual modification. 

 We find, even among these unicellulars (first protophyta, 

 then protozoa) , the important principle which lies at the 

 base of morality, association, or the formation of com- 

 munities. The adaptation of the united cell-individuals 

 to each other and to the common environment is the 

 physiological foundation of the first traces of morality 

 among the protists. All the unicellulars that abandon 

 their isolated eremitic lives, and unite to form com- 

 munities, are compelled to restrict their natural egoism, 

 and make concessions to altruism in the common in- 

 terest. Even in the globular ccenobia of volvox and 

 magosphaera the special form and movement and mode 

 of reproduction are determined by the compromise be- 

 tween the egoistic instincts of the individual cells and 

 the altruistic need of the community. 



Morality, whether we take it in the narrower or 

 broader sense, can always be traced to the physiological 

 function of adaptation, which is closely connected 

 through nutrition with the self-maintenance of the or- 

 ganism. The change in the plasm which adaptation 

 brings about is always based on the chemical energy of 

 metabolism (chapter ix.). H^ce it will be as well to 

 have a clear idea of the nature of adaptation. I defined 

 it as follows in my General Morphology : 



Adaptation or variation is a general physiological function of 

 organisms, closely connected with their radical function of 

 nutrition. It expresses itself in the fact that every organism 

 may be modified by the influence of the environment, and may 

 acquire characters which were wanting in its ancestors. The 

 causes of this variability are chiefly found in a material correla- 



414 



