1 



NTRODUCTION 



"We must interpret the present by the past" (Osborn, 1925). 



"Science had to begin, not with problematical events from the past, but what 



actually happens before our own eyes" (Driesch, 1908). 



"PLANTS and animals cannot exist except in an environment. 

 Those that dominate the earth today have struggled up a long 

 evolutionary trail from the past. They perhaps began, when the 

 earth was hot and even more or less molten, as inorganic substances 

 in which carbon, nitrogen, oxygen, hydrogen, sulphur, iron, and 

 other elements were combining to form such compounds as cyanide 

 (Pfluger, 1875), water, carbon dioxide, ammonia, and acetylene. 

 As the earth cooled, acetaldehyde, aldol, crotonic acid, and pos- 

 sibly even amino-acids formed (Kraft, 1931). At a certain stage 

 in evolution when the environment had attained a stability which 

 somewhat resembled the conditions that prevail today, there came 

 into existence protoplasmic, metabolic, self-sustaining, and self- 

 perpetuating organisms. Once established, organisms began their 

 evolution. As environments varied, many organisms became extinct. 

 A few gradually progressed in complexity and ability and now 

 dominate the earth. Today certain earth animals are able to sit in 

 stable, automatically regulated environments that they have them- 

 selves made, and write treatises on the problems of science. Yet 

 even proud man carries his heritage from the past. His blood plasma 

 has been called archaic sea water; during his embryological devel- 

 opment piscines gill arches appear on the sides of his neck-to-be; in 



3 



