ASPECTS OF KINETIC EVOLUTION 339 



all, to be merely crowds of chromatin granules which are being 

 assembled from the vegetative nucleus for mitapsis, and redis- 

 tributed after mitapsis to resume the functions of control over 

 vegetative growth. 



Adult organisms, with their various characters, do develop out 

 of germ-cells, but until we know something more of the nature 

 of protoplasm, there can be no certainty that the individual char- 

 acters of the adult are in the germ-cell in any such form that 

 we can look in and find them. As well might we undertake to 

 find in human embryos or infants the mental and moral char- 

 acters of adult persons. All that we can be sure of is that the 

 potentialities are there, but the nature, form and residence of 

 these potentialities can be discussed only by means of abstract 

 inferences, and are not yet accessible to the concrete imagina- 

 tion. This explains why the theories of hereditary mechanisms 

 are merely philosophical or mathematical, not biological. Even 

 if the conception were correct and it were possible to ascertain 

 by some extension of microscopic vision that chromosomes or 

 granules are prefigurations of adult organisms, the fact would 

 still have little use as an explanation of heredity, or even as a 

 working hypothesis, until we could learn, or at least imagine, 

 how the models could build the structures. It is as though 

 some barbarous tribe, on being visited for the first time by a 

 modern man-of-war, should think to explain the structure by 

 finding a small model of the ship in a glass case in the saloon. 

 There would simply be two ships to explain, instead of one. 

 Indeed, the discovery of the character-unit mechanism has been 

 so long and so vividly anticipated that it is not altogether unjust 

 to mention the fact that no very definite uses for such a con- 

 trivance have been suggested. 



The studies of Boveri tend to show that in one group, at 

 least, there is a definite necessity for the presence of one full 

 series of chromosomes to make normal development possible, 

 but this is still very far from showing that individual chromo- 

 somes or granules correspond to different parts of the animal. 

 A mutilation or disarrangement of the organs of the germ-cells 

 might well interfere with their development into normal indi- 

 viduals, even if the adult organism were not prefigured, pre- 



