SCOPE OF GENETICS 9 



contributed from two sources, and in respect of 

 any of them he may have received two similar 

 portions or two dissimilar portions. We shall 

 not go far wrong if we extend and elaborate 

 our illustration thus. Let us imagine the 

 contents of a gamete as a fluid made by 

 taking a drop from each of a definite number 

 of bottles in a chest, containing tinctm^es of 

 the several ingredients. There is one such 

 chest from which the male gamete is to be 

 made up, and a similar chest containing a 

 corresponding set of bottles out of which the 

 components of the female gamete are to be 

 taken. But in either chest one or more of 

 the bottles may be empty; then nothing 

 goes in to represent that ingredient from 

 that chest, and if corresponding bottles are 

 empty in both chests, then the individual 

 made on fertilisation by mixing the two 

 collections of drops together does not con- 

 tain the missing ingredient at all. It follows 



^^ 



