General JSTotices. 149 



Scarcely any of the phenomena of the respiration of plants have 

 been hitherto recognized, except the disengagement of carbonic acid 

 gas: and this has been explained by the combination of the oxygen 

 of the air with the carbon of the grain. Thus, according to this 

 theory, the grain is only acted upon by the atmosphere, and the ac- 

 tion of water on the respiration of plants is not to be considered. 

 In the res[)iration of leaves, carbonic acid is evolved during the 

 night, and during the day is absorbed, and oxygen is disengaged by 

 the direct solar rays: and these facts are explained by the supposi- 

 tion that the carbonic acid absorbed is decomposed by the plant, its 

 carbon appropriated, and the oxygen disengaged. But this explan- 

 ation supposes the phmt to possess a decomposing power, which to 

 MM. Edwards and Colin, it seems difficult to admit; and they have, 

 inconsequence, resumed the examination of this function of plants. 



Hitherto, the experiments performed on the respiration of grain, 

 have always been performed in the air; or when they have been 

 j)erformed in water, the ex[)lanation of the phenomena have been 

 limited by what occurs in the air: what has been disengaged in the 

 fluid has not been examined; but this has been done by MM. Ed- 

 wards and Colin. 



They took a globe with a straight neck, the capacity of which was 

 from three to four litres of water, (about one hundred and eighty- 

 three to two hundred and forty-four cubic inches,) with which it was 

 filled; and they then introduced forty large and perfect Windsor 

 beans, (ieves de marais.) To the globe a bent tube was adapted, 

 and which terminated in a jar, also filled with water. The beans 

 were then in contact only with the water and the air which it con- 

 tained, and which could not be removed on account of the mode in 

 which the experiment was performed; and this is an important cir- 

 cumstance, and upon which the success of the experiment depends. 

 The first phenomena which appeared, was the disengagement of 

 bubbles of air arising from the seeds; at the end of twenty-fou" 

 hours the disengagement was considerable. At the expiration of 

 four days, the beans were weighed; they had increased twenty per 

 cent, in weight. When put into the ground, they came up perfectly, 

 which proves that they had suftered no change. As to the produc- 

 tion of gas, that which was disengaged, after passing through the 

 water and being received in the tube or jar, was only a sign of the 

 function: it could be only that portion which the water did not dis- 

 solve as it was gradually formed; it was therefore smaller in quan- 

 tity than that which was dissolved. The quantity of air which had 

 passed through the water without being dissolved, amounted to from 

 twenty to forty millimetres, (1 — 22 to 2 — 44 cubic inches,) but that 

 which was dissolved in the water, and which was expelled from it 

 by ebullition, was very considerable. Before this experiment, the 

 water in the globe contained about 4 — 577 cubic inches of air, and 

 after the experiment, more than 30 — 5 cubic inches of gas were 

 expelled. Thus the action of the beans alone produced nearly thirty 

 cubic inches of gas. No doubt, therefore, can exist, as to the action 

 of water in the resj)iration of the beans. 



It was found that the gas generated consisted of, first, an enormous 

 quantity of carbonic acid; secondly, an almost infinitely small por- 

 tion of oxygen; and thirdly, a very small quantity of a gas which 



