366 M. Dumas on the Chemical Statics of Organized Bei?igs. 



or even Lagrange* had .supposed, but which precisely, as it 

 becomes complicated, tends more and more to enter into the 

 geneial Jaws of inanimate nature? 



You have seen that the venous blood dissolves oxygen and 

 disentratres carbonic acid : that it becomes arterial without 

 producing a trace of heat. It is not then in becoming arterial 

 that the blood produces heat. 



But under the influence of the oxygen absorbed, the soluble 

 matters of the blood change into lactic acid, as MM. Mit- 

 scherlich, Boutron-Charlard and Fremy observed ; the lactic 

 acid is itself converted into lactate of soda ; this latter by a real 

 combustion into carbonate of soda, which a fresh portion of 

 lactic acid decomposes in its turn. This slow and continued 

 succession of phaenomena which constitutes a real combustion, 

 but decomposed at several times, in which we see one of the 

 slow combustions to which M. Chevreul drew attention long 

 ago, this is the true phaenomenon of respiration. The blood 

 then becomes oxygenized in the lungs; it really breathes in 

 the capillaries of all the other organs, there where the com- 

 bustion of carbon and the production of heat principally 

 take place. 



To sum up, then, we see that of the primitive atmosj)here 

 of the earth three great parts liave been formed : 



One which constitutes the actual atmospheric air; the se- 

 cond, which is represented by vegetables, the third by animals. 



Between these three masses, continual exchanges take place: 

 matter descends from the air into plants, enters by this route 

 into animals, and returns to the air according as these make 

 use of it. 



Green vegetables constitute the great laboratory of organic 

 chemistry. It is they which, with carbon, hydrogen, azote, 

 water and oxide of ammonium, slowly build up all the most 

 complex organic matters. 



They receive from the solar rays, under the form of heat 

 or of chemical rays, the powers necessary for this work. 



Animals assimilate or absorb the organic matters formed 

 by plants. They change them by little and little, they de- 

 stroy them. In their organs, new organic substances may 

 come into existence, but they are always substances more sim- 



* The reader will no doubt admire how entirely M. Dumas passes by 

 all English philosophers, — even him with whom these trains of investigation 

 ori'^inated. " This beautiful discovery [of the chemical action of light, heat, 

 and the component parts of atmospheric air upon j)lants], for the main prin- 

 ciples of which we are indebted to Dr. Priestley, shows a mutual depend- 

 ence of the animal and vegetable kingdoms on each other which had never 

 been suspected before his time." — Sir J. E. Smith's Introduction to Botany, 

 see p. 162 — 170. 



