ONLY THE GERM-PLASM IS INBORN 17 



germinal, inborn and inheritable in exactly the same sense. 1 The 

 true distinction between the different classes of characters are 

 indicated when they are described as arising in response to the 

 different classes of stimuli. If the reader still thinks otherwise 

 as he will constantly be tempted to do if he keeps his attention 

 fixed, not on the germ-plasm, but on the individual let him en- 

 deavour to formulate a clear idea as to what makes one character 

 more inborn than another. He will certainly fail. Moreover, if 

 he tries to think of a character of the multicellular individual which 

 is more innate and inheritable than any other, he will succeed only 

 in recalling characters which appear more regularly than others 

 merely because the stimulus which evokes the former is received 

 more certainly than that which evokes the latter. 



32. Occasionally what are known as identical twins are born. 

 They are supposed to be derived from a single fertilized ovum. 

 They are extremely alike, presumably because their germ-plasms 

 were similar. It is conceivable that the germ-plasms might be 

 exactly similar ; in which case, under precisely similar stimuli, 

 they would develop into individuals precisely similar. But if from 

 some cause, for example a twisting of the umbilical cord, one twin 

 received an inferior supply of nutriment, they would differ. Every- 

 one would then agree that the difference, though one of ' innate ' 

 characters, would be acquired ; but it would puzzle anyone to indi- 

 cate the twin that made the differentiating acquirement. 



33. Only the germ-plasm, its structures, and hereditary tend- 

 encies, are really inborn and inheritable; for they really pass 

 from ancestral to descendant germ-cells. The germ-cell is a 

 unicellular organism which, like other unicellular types, divides 

 itself between its offspring, which in turn divide themselves in like 

 manner. The daughter-cells and their descendants, therefore, 

 inherit the structures and qualities of the parent cell in a sense 

 quite different from and much more real than that in which a cell- 

 community ' inherits ' the structures and qualities of the community 

 from whence it is derived. 2 



1 The only conceivable exception is a temporary change, for example, an 

 injury (e.g. a cut) considered apart from the reaction by which it is repaired 

 a reaction which, however, begins at once, or almost at once, by coagulation of 

 blood, etc. Even this exception is more apparent than real, for an injury derives 

 its characteristics not only from the agent which inflicts it, but also from the 

 structure which receives it, which in turn derived its characters from the egg. 



2 It maybe asked " If the germ-cell, the fertilized ovum, divides itself between 



its daughter-cells, which, as well as their descendant cells, repeat the process, how 



does it happen that all the cell-descendants are not close copies of one another 



and of the fertilized ovum whence the community sprang ? Why do some of these 



2 



