SPERMATOCYTES : GYMNOSPERMS 



185 



tion. If the internal structures be considered it is much 

 more. It is made up of structures belonging to three gen- 

 erations, as follows : (1) The old sporophyte is represented 

 by seed coat and nucellus, (2) the endosperm is a gameto- 

 phyte, while (3) the embryo is a young sporophyte. It can 

 hardly be said that the seed is simple in structure, or that 

 any real conception of it can be obtained without approach- 

 ing it by way of the lower groups. 



The organization of the seed checks the growth of the 

 embryo, and this development within the seed is known as 



Fiq. 155. A cycad, ehowine the palm-like habit, with mnch branched leaves and 

 scaly stem.— From " Plant Relations." 



the infra-seminal development. In this condition the em- 

 bryo may continue for a very long time, and it is a ques- 

 tion whether it is death or suspended animation. Is a seed 

 alive ? is not an easy question to answer, for it may be kept 

 in a dried-out condition for years, and then when placed 

 in suitable conditions awaken and put forth a living plant. 



