14 VEGETABLE PHYSIOLOGY. 



of the stomachs of animals that feed on the fruits which contain 

 them, and which are consequently often found deposited at great 

 distances from the plant which produced them ; they are thus fre- 

 quently dropped to germinate and flourish at the tops of the steepest 

 mountains. By these admirable provisions of nature, then, the air, 

 the water, and even animals themselves become the vehicles by 

 which the migration of various vegetable species over the surface 

 of the globe is effected. 



We distinguish in seeds the kernel, and the integument which 

 covers or encloses it. In the kernel, the embryo exists, which, as 

 its name indicates, is destined to reproduce the plant of which the 

 seed is the issue. The embryo is formed of several essential parts : 

 — 1st. of the radicle ; 2d. of the gemmule, plumule, or rudiment o\ 

 the stem, which by its extension engenders the organs that are to 

 vegetate above the ground ; 3d. of cotyledons, which form the great- 

 est portion of the kernel, and which are destined to support the plant 

 during the first periods of its existence. 



In most cases, the cotyledons are formed of two lobes which sepa- 

 rate during the act of germination. The plumule presents itself 

 under the form of a little white point which penetrates into the in- 

 terior of bota cotyledons. The radicle is of a slightly conical shape, 

 and is first seen when it projects externally from the seed. 



The seeds of gramineous plants do not separate into two parts at the 

 commencement of their independent existence. They are, in fact, 

 seeds which have but a single cotyledon. As plants which spring from 

 seeds of one or of more cotyledons present capital dilVerences in 

 their organization at large, and mode of development, botanists have 

 establislied two grand divisions among them — into monocolylcdonous 

 vegetables, and dicotyledonous or polycotylcdonous vegetables. 



When the seed is gathered in its state of perfect maturity it is 

 completely inert, its vital functions are wholly suspended, and it may 

 be kept often for a very long Uinr without beinfr made to grow. 



The length of time during which seeds may be kept, however, 

 varies extremely, according to the species. There are plants, for 

 instance, the seeds of wliich preserve for an indefinite period heir 

 germinative power ; there are others, on the contrary, which lose if 

 very speedily. 



From various observations which appear to deserve every con- 

 fidence, the seeds — 



Of Tobacco have porininatod after liaving boon 



kept for 10 years. 



" Stranioniuin 2o " (Duhaiiiel.) 



•' the Sensitive plant 60 " 



"Wheat 1(10 " (Pliny.) 



"Wheat 10 " (Duhamel.) 



"Melons 41 " (Friewald.) 



"Cucumbers 17 " (Roger Galen.; 



" Haricots 33 " 



"Mem 100 " (Genrdin.) 



"Rape 17 " (LetV-l.-m*.) 



"Rye 140 " (Home.) 



The seeds of the cotTee plant arc perhaps those which lose the 



