XX GERMINATION 217 



period of rest, it germinates. The process begins by the 

 division of the oosperm into two cells, a small one nearest 

 the crown and composed almost wholly of protoplasm, and 

 a larger one full of starch granules. The larger cell serves 

 simply as a store of nutriment to the growing plant which 

 is itself developed exclusively from the small cell. The 

 latter divides into two cells one of which grows downwards 

 as a root-fibre, the other upwards as a shoot, consisting at 

 first of a single row of cells (Fig, 48). Soon two nodes {nd) 

 are formed on the filament, or embryo, from the lower of 

 which rhizoids (rh) proceed, while the upper gives rise to a 

 few leaves (/), and to a small process which is at first uni- 

 cellular, but, behaving like an apical cell of Nitella, soon 

 becomes a terminal bud {tertn. bud) and grows into the 

 adult plant. 



It will be seen that the development of Nitella is remark- 

 able for the facts that the adult plant is not formed directly 

 from the oosperm but that the latter gives rise to an embryo, 

 quite different from the adult in structure, and that, from 

 the embryo, the adult is finally developed as a lateral bud. 



