PROVOCATIVE BIOLOGICAL THEORIES 89 



knowledge and control of the environmental agents im- 

 pinging upon such organisms, or a mere understanding of 

 the physics and chemistry of the separate substances of 

 which they are composed, can never suffice to bring about 

 a real understanding of what it all means. "The same 

 materials, under action of the same agents, respond in 

 most diverse ways, depending on how the materials are 

 arranged." 



Changes of organization take place when the develop- 

 ing organism is subjected to special or unusual condi- 

 tions, such as the growing of a head in place of a tail. One 

 might expect to find here, then, the secret of biology, as 

 such changes may take place in the grosser as well as the 

 more minute details of organization. But such changes 

 all disappear with the individuals in which they appear. 

 They are not carried on to their respective offspring. Con- 

 sequently, these things cannot account for the permanent 

 differences of systems found among organisms, and it is 

 just the permanent and hereditary diversities which form 

 the deepest problem of biology. 



Since all organisms are but protoplasmic substances, 

 why is it that some are different from others ? How, and 

 according to what rules, have these changes occurred? 

 What is the environment in a given case, and what effect 

 does it produce on the organism? What are the physics 

 and the chemistry of the diverse substances of the organ- 

 ism? How are the diverse substances arranged? How 

 combined into systems ? What diversity do these systems, 



