258 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 po.-terior end of the 

 embryo. 



Note that there is no definite boundary between 

 the suspensor and the embryo. Also that though 

 polyembryony is the rule that is, 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 cutting sections of ovules taken between the dates above 

 named, and treating them in the manner described for the cones 

 taken in June, the history of the early stages of development 

 of the suspensors and embryos from the fertilized ovum 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 seed-coat : within this the endosperm, which 

 incloses the single embryo. It has numerous cotyle- 

 dons, and a radicle, the apex of which is 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, 



