160 PRACTICAL BOTANY. 



c. The apex of the Radicle, directed towards the 

 suspensor (i.e. towards the micropyle of the ovule), and 

 embedded in the tissue at the posterior end of the 

 embryo. 



Note that there is no definite boundary between the 

 suspensor and the embryo. 



Also that though polyembryony is the rule, i.e. a 

 number of embryos are at first formed simultaneously, 

 one of these supersedes the rest, and that one alone 

 becomes differentiated as above described. 



By comparing sections of ovules of various ages (i.e., taken 

 between the dates above named), cut and treated in the manner 

 described for the cones taken in June [p. 158], the history of the 

 early stages of development of the suspensors and embryos from 

 the fertilised egg-cell may be traced. 



Ripe Seed. 



Examine the ripe seed of P. sylvestris, or other 

 species e.g. P.pinea; and note the external hard and 

 thick Testa; within this the Endosperm, which 

 incloses the single Embryo. It has numerous Cotyle- 

 dons and Radicle, the apex of the latter being directed 

 towards the micropyle. 



Germination. 



Compare plants in different stages of germination, 

 and observe the following points in the process : 



1. The endosperm swells, and bursts the testa. 



2. The radicle protrudes, and curves downwards. 



3. The cotyledons elongate, and push out the stem, 

 and their own basal portion* 



