The Visible Basis of Heredity 75 



the half-number (haploid number) in each unite 

 and make up the usual (diploid) number once 

 more. This takes place in animals usually very 

 soon after the reduction division has occurred; 

 but in plants the union may be long delayed, 

 for the spore does not at once produce the germ 

 ceUs, but the sporophyte, whose tissue then 

 consists of cells with the haploid number of 

 chromosomes. 



There is very good evidence that even when 

 these chromosomes seem to lose their identity 

 in the newly formed nuclei they really do not. 

 When, for instance, two animals of similar but 

 stiU unlike species, such as different sorts of 

 minnows, are used as parents, the chromosomes 

 in the germ cells are of such different shapes that 

 they can be recognized in the equatorial-plate 

 stage of the successive divisions of the fertilized 

 egg and even in the divisions of tissue cells in 

 the weU-developed young fish. In some plant 

 cells the swoUen and alveolar chromosomes can 

 be distinguished apparently even in cells that are 

 in the resting stages. Biologists are inclined to 

 believe that chromosomes retain their identity. 



