8 



CELL GENETICS 



the production of the female germ-cells, as in the higher plants) 

 an intermediate condition is found. The four potential spores are 

 almost equal ; the gametophyte may then develop from one (cf. 

 CEnothera, Ch. IX), or from the collaboration of all four. 

 It is of particular importance in studying the mechanism and 



DfJt>/o/dJsah'on ^ ^ '^ n*n 



fusion melosis 



n-^n 



Mycelium 3asi}}i am S/^ores 



Fig. 2. — Life cycle of a basidiomycete, showing diploidisation, by 

 which the haplophase becomes a diplophase, the division of 

 conjugate nuclei and the cells containing them, and the occur- 

 rence of meiosis immediately after the fusion of these haploid 

 nuclei {cf. Buller, 1931). 



material basis of heredity to examine the male gamete — sperm, 

 " antherozoid " or "generative nucleus" of the pollen grain. The 

 female gamete is usually an over-developed cell, the male an under- 

 developed one ; that is to say, its constituents are reduced, and 

 by studying their reduction we can see what is essential, and 

 what unessential, in carrying the contribution of one parent in 

 heredity. 



