120 



M. L. Garreau on the Functions of 



it as a natural result. We may here recall some experiments 

 made by De Saussurc, Dutrochet, and Adolphe Brogniart^ as sup- 

 plementary to those which we can ourselves adduce in support 

 of the same truth. 



Dutrochethas demonstrated ('Annales des Sciences Naturelles/ 

 1845, p. 5) that all parts of plants possess a degree of heat 

 superior to that of their surrounding medium, and that the 

 elevation of temperature noticed in the Arum, the Caladium, &c., 

 is only a more marked manifestation of a phenomenon common 

 to all living beings. But this phenomenon itself is nothing 

 more than a feeble reflex of a more material fact, viz., that of 

 the chemico-vital combustion of carbon by oxygen. Thus, in 

 the instance of plants as of animals, the respiratory act has for 

 its final appreciable result to carry off carbon and to raise their 

 temperature ; and these two effects are intimately correlated in 

 both sets of organisms ; for the researches of De Saussure show 

 that tubers, roots, ligneous stems, &c., give ofi* only one-half of 

 their volume of carbonic acid in the twenty-four hours; whilst 

 those of Dutrochet have demonstrated that the heat belonging 

 to those parts is scarcely appreciable. 



The former of these observers has remarked that in monoe- 

 cious flowers the males consume more oxygen than the females ; 

 and the latter has noticed that their temperature is also more 

 elevated. The researches of Sennebier on the heat of Arum 

 maculatum, those of Schultz on Caladium pinnatifidum, those of 

 Goeppert on Arum dracunculus, of Brongniart, Vrolicke, and 

 Vriese on Colocasia odora, as well as those long ago made by 

 Lamarck, and our own on the spadix of Arum italicum, establish 

 most distinctly the cause of the phenomenon and its relations 

 with the oxygen and the carbon consumed. The following Table 

 of the heat of certain plants, and of the quantity of carbonic acid 

 expired by them during a certain time, represents the approxi- 

 mative results arrived at by Dutrochet and other observers : — 



Name of plants. 



Oxygen 

 consumed 

 in 24 hours, 



Observer. 



GreenPear 



Green Pear 



Plum {Reine Claude) 



10 grs. of leaves of House-leek 

 Spathe of Arum maculatum... 



Spadix of do 



Stamens of do 



Pistils of do 



Flower of the Gourd 



Boletus aureus 



050 



0-70 



1-60 



0-20 



400 



3800 



13500 



1000 



7-60 



7-50 



Dutrochet. 

 Id. 

 Id. 

 Id. 

 Id. 

 Id. 

 Id. 

 Id. 

 De Saussure. 

 Dutrochet. 



From these facts, derived from different sources, it is at once 



