VARIATION AND HEREDITY 5 



due of unaltered germinal material is kept apart to form 

 the reproductive cells, one of which may become the 

 starting point of a child. On this point Galton has writ- 

 ten, "The total heritage of each man must include a 

 greater variety of material than was utilized in forming 

 his personal structure. The existence in some form of 

 an unused portion is proven by his power ... of trans- 

 mitting ancestral characters that he did not personally 

 exhibit. Therefore the organized structure of each in- 

 dividual should be viewed as the fulfilment of only one 

 out of an indefinite number of mutually exclusive possi- 

 bilities. His structure is the coherent and more or less 

 stable development of what is no more than an imperfect 

 sample of a large variety of elements." 3 The idea was 

 more independently expressed and more fully developed 

 by Weismann in 1893. 4 It is now the basis of our expla- 

 nation of why like tends to beget like. It is the theory of 

 the continuity of germinal plasm. Weismann says, "In 

 development a part of the germ-plasm (i. e., the essential 

 germ material) contained in the parent egg-cell is not 

 used up in the construction of the body of the offspring, 

 but is reserved unchanged for the formation of the germ- 

 cells of the following generation." Thus it has been 

 said that the parent is rather the trustee of the germ- 

 plasm than the producer of the child. The philosopher 

 Bergson has said, "Life is like a current passing from 

 germ to germ through the medium of a developed or- 

 ganism. . . . The essential thing is the continuous prog- 

 ress indefinitely pursued, an invisible progress, on which 

 each visible organism rides during the short interval of 

 time given it to live." The reason why like tends to 



s Galton, F. Natural Inheritance, 1889, p. 18. 



* Thomson, J. A., & Geddes, P. Evolution, 1911, p. 114. 



