250 PRINCIPLES OF BOTANY, ETC. 
When the seed is placed in the ground, moisture 
soon pervades its substance through this aperture, 
assisted by the warmth of the AeROUBHE Te In the 
corcle and cotyledons all the before described ves- 
sels are present. Inthe last the adducent and air 
vessels divide themselves in numberless bundles, 
which frequently anastomose, (§ 238). A cellular 
membrane covers on both sides those vessels which 
spread on one plain surface, and contains the redu- 
cent vessels. On both surfaces the lymphatics spread 
out and surround the apertures of the cuticle. The 
pervading moisture is taken up by the vessels; the 
water 1s decomposed by them, and hydrogen and 
oxygen transpired. Carbonic acid gas, which seems 
to be shut up in the neighbourhood of the umbilicus 
by the external and internal membranes of the seed 
is likewise set free. The’ gaseous fluid, which was 
received from germinating seeds, contained in 10 
cubic inches, sometimes 2, sometimes 3, 5, even 
8 cubic inches of carbonic acid gas; and from 5 and 
6 to 8 cubic inches of azote and hydrogen gas 
mixed. “This gas, v when coming in contact with the 
oxygen of the atmosphere, exploded at the approach 
of a candle. “The rest’ of the undecomposed water, 
with the fixed part of carbon’ and hydrogen, per- 
vades the vessels more and more, attenuates the 
substance of the seed to a milk-white fluid, and ex- 
cites thé action’ of the vital power. The vessels, 
filled with their sap, carry it to the corcle, which 
is elongated by it, and converted into a plant. 
The corcle consists, as we saw, (§ 114), of the 
rostel, (rostellum), and the plumule, ( plumula). 
¥rom 
