ORGANIC EVOLUTION — THE FACTORS 121 



But, as we see, variations can only be reproduced in the 

 offspring by exercise of it, since without stimulation the 

 variations do not appear. Therefore Mr. Spencer and 

 those who follow him virtually hold that the acquire- 

 ment of variations by the parent causes an increased 

 power of varying in the offspring ; i. e. that when one 

 thing is acquired, another thing, which is not ac- 

 quired and is therefore not transmitted, appears in 

 the offspring. 



