M. Dumas on the Chemical Statics of Organized Beings. 465 



haling in the air; soluble, so that it may be taken up again by 

 rain ; and consequently destined thus to travel from the earth 

 to the air and from the air to the earth, until, pumped up by 

 the roots of a plant and elaborated by it, it is converted anew 

 into an organic matter. 



Let us add another feature to this picture. In the urine, 

 along with urea, nature has placed some traces of albuminous 

 or mucous animal matter, traces which are barely sensible to 

 analysis. This, however, when it has reached the air, is there 

 modified, and becomes one of those ferments of which we find 

 so many in organic nature; it is this which determines the 

 conversion of urea into carbonate of ammonia. 



These ferments, which have so powerfully attracted our 

 attention, and which preside over the most remarkable me- 

 tamorphoses of organic chemistry, I reserve for the next year, 

 when I shall give you a still more particular and full account 

 of them. 



Thus we discharge urea accompanied by this ferment, by 

 this artifice, which acting at a given moment, turns this urea 

 into carbonate of ammonia. 



If we restore to the general phaenomenon of animal com- 

 bustion that carbonic acid of the carbonate of ammonia which 

 of right belongs to it, there remains ammonia as the charac- 

 teristic product of urine. 



Thus, by the lungs and the skin, carbonic acid, water, azote ; 



By the urine, ammonia. 



Such are the constant and necessary products which exhale 

 from the animal. 



These are precisely those which vegetation demands and 

 makes use of, just as the vegetable in its turn gives back to 

 the air the oxygen which the animal has consumed. 



Whence come this carbon, this hydrogen burnt by the 

 animal, this azote which it has exhaled in a free state or con- 

 verted into ammonia? They evidently come from the ali- 

 ments. 



By studying digestion in this point of view, we have been 

 led to consider it in a manner much more simple than is 

 customary, and which may be summed up in a few words. 



In fact, as soon as it was proved to us that the animal cre- 

 ates no organic matter; that it merely assimilates or expends 

 it by burning it {en la brixlant)^ there was no occasion to seek 

 in digestion all those mysteries which we were quite sure of 

 not finding there. 



Thus digestion is indeed but a simple function of absorp- 

 tion. The soluble matters pass into the blood, for the most 

 part unchanged ; the insoluble matters reach the chyle, 



Phil. Mag, S. 3. Vol. 19. No, 126. Dec. 1841. 2 H 



