210 



Practical Plant Biology. 



just as the endosperm contained in the megaspore or embryo-sac 

 is homologous to the female gametophyte of Selaginella. The 

 female gametophyte of the latter possesses chloroplasts and 

 produces rhizoids and consequently is at least partly independent 

 and self-supporting, but the male gametophyte is dependent for its 

 supplies throughout its short life on the stores laid up by the 

 sporophyte. Neither of the gametophytes of the pine show any 



FIG. 69. <-Pinus silvestris, seed 

 longitudinal section, x g, a, 

 seed-coat; 6, endosperm; c t 

 cotyledons ; d, root ; e, sus- 

 pensor. 



FIG. 70. Pinus, germinating 

 seed and seedling, x 3. (After 

 Sachs.) 



independence of the sporophyte, but both, like the male game- 

 tophyte of Selaginella, are wholly dependent on the sporophyte for 

 their food. The dependence even appears to go further, for both 

 require in addition the nursing attention of the living cells of the 

 parent sporophyte to administer the food to them. Their attitude 

 towards the sporophyte may thus be compared to that of a child 

 towards its nurse or of a parasite towards its host. Evidently 

 while the sporophyte has gained in importance and complexity the 

 gametophyte is reduced in size and independence. 



