AS THE ELEMENTAL GERM OF AN ORGANISM 353 



After this period, which, by the way, would be reached in a few 

 years in the case of low, quickly-multiplying organisms, formation 

 of the hereditary mass would be obliged to take place with each 

 fresh act of fertilisation, in consequence of the impossibility of 

 diminishing the ancestral plasms any further, nnless some other 

 arrangement be made. Weismann considers, that this new arrange- 

 ment consists in this, that, when the sexual products are mature, 

 half of the ancestral plasms are ejected from the hereditary mass 

 in the pole-cells, before fertilisation occurs. In place of the 

 division of the individual ancestral plasms, therefore, the division 

 of the total number of plasms takes place after they have become 

 no longer divisible as units. 



Thus, according to Weismann's assumption, the hereditary mass 

 is an extremely complicated piece of mosaic, composed of innumer- 

 able units, the ancestral plasms, which, by their very nature are 

 indivisible and incapable of mixing with other units, and each of 

 which in its turn is composed of numerous elemental germs, which 

 are necessary for the production of a complete individual. 



Thus, every hereditary mass, in consequence of its composition, 

 would have to produce countless individuals, if each ancestral 

 plasm were to be active. The essential nature of the process of 

 fertilisation lends itself to a combination and elimination of an- 

 cestral plasms. Further, if the ancestral plasm theory were 

 true, elemental germs of equal value would accumulate in the 

 hereditary mass. In fact the generative individuals belonging 

 to the same species are essentially similar in their properties, if 

 we disregard small individual differences of coloration. All the 

 ancestral plasms must, therefore, contain essentially the same 

 elemental germs. These various germs are represented in the 

 hereditary mass as many times as there are ancestral plasms, 

 the majority being similar to one another, and only presenting 

 differences of shade. But all these similar, or slightly different, 

 elemental germs would stand in no direct relation to each other, 

 since they must remain integral component parts of the ancestral 

 plasms, for which we have assumed indivisibility. 



The question of heredity, instead of being simplified by Weis- 

 mann's theory of ancestral plasms, is rendered more complicated 

 by it, especially by the assumption that the paternal and maternal 

 hereditary masses are incapable of mixing with one another. 



I cannot see that this theory of Weismann's is of any great 

 use, since it leads to so many difficulties, which appear to be 



A. A 



