tion ; for it neither changes the taste, the odour, nor 
any other properties of the seed *. 
203. To that swelling of the seed which consti- 
tutes germination, M. Scheele considered the presence 
of oxygen gas in the water to be necessary, and as- 
serted that this gas was converted into carbonic acidf. 
According, also, to M. de Saussure, peas and other 
seeds germinate in water that contains oxygen, but 
do not properly unfold their radicles in boiled water, 
when the water does not exceed more than seven or 
eight times the weight of the seed ; but when it is 
one or 20O times as great, the radicles have then been 
prolonged. This happens, says he, because ebulli- 
tion does not entirely deprive water of its air, and 
when, therefore, the quantity of this fluid is suffi- 
ciently large, enough of air is present to excite a fee- 
ble development of the seed J. 
204. Water enters into the seed, partly through 
the pores of its external coat, and partly through the 
small opening placed in the hilum or scar. M. Se- 
nebier asserts, that if the opening in this scar be clo- 
sed, the swelling or germination of the seed is pre- 
vented ; but in some experiments made by Dr Jones, 
this was not found to happen. He placed some large 
beans in a saucer of mould with the opening in the 
scar uppermost, and watered them in such a manner 
that the fluid could not enter it, and yet they seemed 
to germinate in the ordinary time. 
* Recherches Clum. sur la Vegetation, p. 2. 
f On Air and Fire, p. 167. J Recherches, p. 3. 
Mem. Physico-Chimiques, torn. iii. p. 333. 
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