ON THE STUUeXURE AND GROV^^TH OF SEEDS. -T 



be known, that impregnation had taken place. On the con- 

 trary, the alertness of Nature is such, that often in 48 

 hours tlie corculunti is filled, the impregnating line runs 

 through the heart, and the increase of the nourishing vessels 

 is visible. The line stops when the cotyledons shoot, but 

 they do not yet appear. 



lu the second stage of this period tlie spreading of the 2d stage of the 

 nourishing vessels is astonishing ; the pocket and corculum l^sri'^Q- 

 join; and the cotyledons begin to grow. All this time no 

 radicle appears, though the cotyledons have almost com- 

 pleted their form. It is in this state of advancement, that 

 the seed declares whether it is a seed leaf, or common seed: Two divisions 

 for these two forms divide almost the whole assemblage of °' ^^'^^^^ 

 seeds. 



The conclusion of the second period shows the cotyle- Last s'age of 

 dons in their natural form : that is, either with two little ^J;'^ 2d period. 

 silvery thin leaves, perfectly white; yr with two thick yel^ 

 low /eaves, which afterward, rising with the plant, turn 

 green, and are seen above the earth. I have never seen * 



more than two, except in the fir tribe and some of the 

 grasses ; and in the cress and mustard seed, the former of 

 which has six cotyledons, and the latter four. This perhaps 

 accounts for their springing so quickly out of the earth. 

 With respect to the monocotyledons and dicotyledons I 

 shall say a few words toward the conclusion of my letter, as 

 I am perfectly convinced with Wildenouw, that the divisipn 

 is erroneous. This is the time for proving, that no radicle 

 is yet to be seen. Where is the radicle in these seeds ready 

 for planting, and prepared for it? see figs. 15 — 21. 



When the radicle begins to shoot (and its work is soon Radicle, 

 done), the primordial leaves also shovy themselves between 

 the cotyledons, see figs. 22 — 25: and it is in this stage, that 

 the holders begin to grow, where there are such yjarts in the 

 seeds; for few ])!ants, in comparison of the innumerable 

 species, have litem. In some of the diadelphian tribe inr 

 deed they grow sooner, particularly in the beans. At the 

 termination of the second period too is seen the use pf that 

 part in the seed, which is formed with peculiar strength, 

 and not only marked where the vessels enter, but whicli u 

 Rouble cuticle covers; either ^n a cirfula^ spot, as in the 



(Itestnul I 



