M. Dutrochet on the Temperalute of Teg edibles. 109 



result of this experiment was to indicate to me a higher tem- 

 peratm*e in the dead branch than in the living one, and that 

 with ii-regular variations in intensity ; I observed the devia- 

 tion of the magnetic middle from hour to hour. The follow- 

 ing day I replaced the dry branch by a green branch of the 

 same plant, but one which I had deprived of life by plunging 

 it for five minutes in water heated to 50° (122° F.), a heat not 

 stifficient to boil it in any degree. I then left it to cool. In 

 this second experiment I obtained an opposite result, for it 

 was invariably the living branch which exhibited the gi'eatest 

 degree of heat, and that with irregular variations. The con- 

 tradictory results of these two experiments, gave me reason 

 to think, that the cooling produced by the evaporation of the 

 fluids contained in these branches, was the cause of the stfange 

 differences which manifested themselves between their recipro- 

 cal temperatures. The living branch being placed in com- 

 parison with the dead and dried one, the first experienced, 

 OAving to the evaporation of its fluids, a cooling which the se- 

 cond by no means suff'ered, so that the latter possessed the 

 largest amount of heat. 



When the living branch was placed in comparison with the 

 dead one, which was still filled with its sap, these two branches 

 were cooled unequally, owing to the unequal evaporation of 

 their fluids ; an evaporation much more considerable in the 

 dead branch than in the living one, so that the latter ought 

 thus to manifest a higher temperature. I have indeed found, 

 that under the influence of the same external causes, the eva- 

 poration is more considerable in the dead branches than iu the 

 living ones of the same dimensions. This fact proAes, that 

 these living vegetables exercise an action which tends partly 

 to remove a part of their organic liquids from the dissolving 

 action of the atmosphere. The living branch only gives up 

 to evaporation what it exhales, a phenomenon both physiolo- 

 gical and physical ; while the dead branch gives up its liquids 

 to evaporation, just like a moistened piece of cloth, a pheno- 

 menon purely physical. M. Becquerel does not say in his 

 note if the dead branch which he employed in his experiment 

 was dried, or if it still possessed a part of its sap. It appears 

 to me very probable, from the result of his experiment, that 

 the latter is the truth, liut, I return to my two experiments 



