30 i THE AMERICAN NATURALIST [Vol. LI V 



the fundamental attributes of protoplasm. The manner 

 of the response is adaptive, it is an individual effort, and 

 is usually non-transmissible. "Whether the responses 

 ever become transmissible, in that they appear without 

 the original stimulus, is the crucial point of the problem 

 of the transmission of acquired characters. That the 

 organism has the inherent power of forming new non- 

 germinal characters is however not questioned, and it is 

 well that the hard fact should be kept in mind. What we 

 desire is some evidence that stimuli are transmissible or, 

 if this be not forthcoming, some proof that the responses 

 may appear without the original stimuli. At first this 

 may be deemed to be looking for an effect without a cause, 

 a response without a stimulus. 



The callosities in the ostrich and adaptive responses 

 generally lead one to submit that a character may become 

 transmissible without necessarily being germinal, in the 

 sense of having factorial representation in the germ 

 plasm. Acquired characters are such somatic modifica- 

 tions as are produced as responses of the organs and 

 tissues to stimuli, and are without direct representation 

 in the germ plasm. In the words of Weismann: " Ac- 

 quired characters are those which result from external 

 influence upon the organism, in contrast to such as spring 

 from the constitution of the germ." 9 They reveal an in- 

 herent power of response of the tissues and organs in a 

 more or less definite manner according to the differentia- 

 tion of the tissues and the nature of the stimulus. It 

 may be that much of the complicated development of 

 to-day was primarily of the nature of responses to stimuli. 



The acceptance of Weismann's germ plasm theory of 

 inheritance, strengthened as it lias been by the factorial 

 hypothesis, has for the past two or three decades concen- 



