ORGANS OF REPRODUCTION. 119 



oil plant ; but M. A. Richard denies the existence of 

 two different membranes. Malpighi and Grew however 

 mention an outer coat, still different and more deli- 

 cate ] ; and Grew one still within Gaertner's inner 

 coat, immediately investing the seed. 



The shell of the seed, like that of eggs, is so com- 

 posed as to protect them from extremes of heat and 

 cold ; but that of seeds will remain uncorrupted for 

 many years, so that wheat, found with mummies pro- 

 bably 3000 years old, has been made to germinate. 



What becomes the shell of the seed consists, in the 

 unripe seed, of two envelopes, one including the other, 

 and these including, according to M. Mirbel, three 

 others, but all five united in some part of their texture. 

 The outer is termed primine ; the next, secundine; the 

 three inner collectively, the kernel ; and severally, ter- 

 cine, quartine, and quintine; the last being the centre 

 of the kernel. When in the progress of ripening the 

 base of the kernel rises partially, or altogether, to the 

 tip of the seed, it remains connected with that base by 

 certain vessels termed the vascular cord 2 , and when 

 this cord expands at the base of the kernel it is termed 

 the ball 3 . 



The shell, viewing it in ripe seeds, envelopes the 

 more essential part termed the kernel 4 , which in some 

 instances is composed of one body only, termed the 

 embryo ; and in others, besides this, what may be 



(1) In Latin, Pelicula. (2; In Latin, Raphe. 



(3) In Latin, Chalaza. (4) In Latin, Nucleus. 



