EXPLANATOEY HYPOTHESES 107 



known to be a very complicated substance, especially 

 that composing the nucleus, which contains a 

 number of elongated chromosomes, which split 

 lengthways when the cell divides. Professor 

 Weisman supposes that the chromosomes alone bear 

 the hereditary characters, and that they are made up 

 of minute particles called biophores, which combine 

 into determinants ; these are grouped into ids and 

 the ids into idants. There is a determinant for each 

 part of the body ; and , as the germ develops , one 

 half goes to the new germ cell, the other grows into 

 the body of the organism. That portion which 

 passes from the germ cell of one generation directly 

 to the germ cell of the next generation he calls 

 germ-plasm. That portion which goes to build up 

 the body he calls somato-plasm. 



At first he thought that acquired variations could 

 not be transmitted, and that all variations were 

 brought about by amphimixis. But, being convinced 

 that this was a mistake, and being impressed with 

 the importance of definite variation, he proposed, in 

 1895, the hypothesis of Germinal Selection 24 to 

 account for it and for degeneration. This hypo- 

 thesis is that in the inevitable fluctuation of the 

 nutrient supply, some determinants in each cell will 

 obtain more nourishment than others, and will 

 develop into more strongly marked characters. If 

 the individual bearing one or more of these charac- 

 ters is selected, this would favour the more powerful 

 determinants of those characters, and if this selec- 



24 English translation in the " Religion of Science 

 Library," Chicago. 



