336 Extracts. [June, 



EXTRACTS. 



M. dutrochet's views of the breathing of vegetables. 



M. Dutrochet, who is already distinguished in the scientific 

 world, for his able experiments on vegetable physiology, has re- 

 cently laid some further information on the same subject before 

 the French Academy of Sciences. Having observed that the 

 pneumatic organs in different parts of the MymphcBa lutea con- 

 tained an air in which there was less oxygen in proportion as 

 these parts were distant from the leaves, it struck him, that the 

 leaves were the sources whence these organs derived their oxygen, 

 and that this oxygen was disposed of by the breathing of the 

 plant, as in animals. After stating his observations at great 

 length, he continues as follows: — The results of these experiments 

 are, that the oxygen produced by the leaves under the influence 

 of light, is first poured into the pneumatic cavities: into these it 

 is pressed into continued accumulation, and escapes to the outer 

 surface by means of the tracheae, the orifices of which are situated 

 in the air, and on the leaves. Most of the aquatic plants have 

 these orifices so contrived, as not to be entirely closed when in 

 contact with the water, but a few are without these mouths, and 

 then the oxygen is crowded into the pneumatic canals of the foot- 

 stalks, and from thence is pressed into the stem, which accounts 

 for the enormous quantity of water contained in some of the 

 aquatic plants. We may then conclude, that vegetables breathe 

 like animals, that is, by assimilating the oxygen which they in- 

 troduce into their respiratory organs; but instead of borrowing 

 this from the surrounding air, they fabricate it, and that which 

 they give out is, in reality, the overflowing of their respiratory 

 organs. The leaves are the organs used in this fabrication, and 

 when they have filled themselves, they send it on into the stem, 

 and as the quantity exceeds the physiological wants of the plant, 

 it is abundantly poured out. The pneumatic organs, which serve 

 as a resoirvoir for breathing air, are generally placed on the un- 

 der side of the leaves, and when leaves that are intended by nature 

 to remain in a certain position are reversed, they will die, that is, 

 they will cease to produce the respiratory oxygen, and will be 

 suffocated; though it is not yet ascertained why leaves, in order 

 to produce this oxygen in a healthy and durable manner, should 

 necessarily have that side exposed to the light which is opposite 

 to their resorvoirs of air. The direct and healthy manner of 

 breathing in vegetables, consists of the production of oxygen under 

 the influence of light; therefore darkness is unfavorable to vege- 

 table life, and injures the durability of the plant. The life of the 

 corolla} is ephemeral, because these parts do not manufacture re- 



