THE LAWS OF HEREDITY 



CHICKEN VERSUS EGG 



When we consider the germ-plasm in this light, 

 its transmission of hereditary qualities seems in 

 a sense simple and unavoidable. 



But if we consider the matter a little more at- 

 tentively it will appear that the germ-cell retains 

 no small measure of mysteriousness. We agreed 

 that there was nothing mysterious about the fact 

 that the single-celled organism say the bac- 

 terium transmits its qualities, inasmuch as its 

 entire body is bisected. But, although we have 

 likened the germ-cells to a single-celled organism 

 which in point of fact it externally resembles 

 we cannot proceed far without noting the vital 

 fact that the germ-cell carries the potentialities 

 not merely of other germ-cells like itself, but of 

 body-cells in endless profusion that go to make up 

 the complex organism let us say of a tree or of 

 a man. 



How is it conceivable that a germ-cell of mi- 

 croscopic size shall carry forward such poten- 

 tialities, and carry them so definitely that they 

 predetermine with absolute accuracy the form of 

 every leaf on the tree, or the color of the eyes, the 

 complexion, and the mental qualities of the man? 



As to that, no one can give a really valid an- 

 swer. That the germ-cell does convey these po- 

 tentialities is familiar matter of fact. How it can 

 convey them seems at first thought absolutely in- 

 comprehensible. But philosophers in all ages 

 have puzzled over the matter, and there have been 



[269] 



