ON THE STRUCTURE AND GROWTH OF SEEDS, 3, 



these mix much with the vessels of the seed, if the latter are 

 not previously well known, they are but too apt to produce a 

 very great confusion. 



When the bud of the flower first appears, it is a notice Commeace- 

 Nature gives, that the seed has received life. It is then "^'="^of li^eia 



, ,• , 1 , , , ,- ■ the seed. 



tune to delineate the seed vessel, when we can best distin- 

 guish all the vessels of consequence, and perceive from 

 which part they come, and for what office they are ordained. 

 They are of three sorts. First, the impregnating, or vessel Three sorts of 

 of life. This is always found in the middle of the seed ves- ^f^^^sls m it, 



1 T , ' r. 1 ' 1 1 • 1 • Vessel of life* 



sel, proceeds directly from between tne wood and pith m 



the stem of the tree, and becomes only the impregnating 



duct, when after entering the pistil it mounts to the stigma, 



and there receives the flower of the stamen, to mix with its 



own juices. Mirbel says, " The vessels of the style unite Mistake of 



in the placenta, with those of the peduncle, and compose ^^^^" 



with them the uaibiiical cord." This is certainly a mistake: 



for the style is merely a sheath for the vessel of life, which 



only becomes the impregnating or umhiJical vessel, when it 



returns from the stigma, conveying to the corculum of 



each seed the join^ jM?c^5. This string! have often taken 



out at its length, after boiling away the pulpy part, and I 



could never perceive it was joined to any otUer. 



The second is a sjet of vessels called the nouriahiog ves- Nourishing 

 sels. These have not been long discovered, and I believe I ^^^''^ *' 

 was the first botanist that announced them. They run frpra 

 the bark and inner bark, and bring not only support to the 

 embryo, but the resins, oil, &c. for the formation of the 

 young leaves. They enter the seed in bundles, and are by 

 degrees disseminated all over it. 



The third vessel is a single one, and contains the hidro- Vessel con- 

 gen. It proceeds from the exterior of the plant, and enters taming hidro- 

 at the back of the corculum or heart of the seed ; but not 

 till the formation is almost complete. It may indeed be 

 said to give it the last finishing touch. 



There are also three periods in the life of the embryo Three periods 

 plant, concluding with its no longer meriting this name, '" *^^^ ^*^^ ''^ 

 which, for want of being properly discriminated, have caused 

 the greatest confusion among botanists. The first is from 

 the time the seed appears in its seed vessel to its iropregna- 

 B2 tion; 



