INDIVIDUALS AND SPECIES 35 



pie that all life arises from preexisting life is suffi- 

 ciently established to condition our studies of 

 living things. Consequently we may conclude that 

 all organisms begin life with a heritage character- 

 istic of their ancestral line. From the moment of 

 conception they have certain possibilities. Grant- 

 ing that the reproductive body meets a favorable 

 environment, be it spore, fertilized ovum, or any 

 of the numerous other forms in which the organ- 

 ism may first become independent of its parents, 

 the heritage will proceed to develop according to 

 its inherent possibilities. Once developed into an 

 adult organism, it continues to exist by virtue of 

 the constant interchange which it is able to main- 

 tain with its environment. This idea has been 

 especially well expressed by Dendy ^ in the follow- 

 ing words: "It appears, then, that an organism 

 really inherits from its parents two things: (1) a 

 certain amount of protoplasm loaded with poten- 

 tial energy, with which to begin operations, and 

 (2) an appropriate environment. . . . Therefore, 

 when we say that an organism inherits a particular 

 character from its parents, all we mean is that it 

 inherits the power to produce that character under 

 influence of certain environmental stimuli." 



The essential nature of both factors is evident 

 throughout all stages of development, although it 

 is impossible in many cases to say what stimulus 



7 Am. NaU Vol. XLIX, p. 161, 1915. 



