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animal economy, to a process which is perfectly consistent and 

 analogous with the well-known chemical hearings of this substance 

 apart from the animal system. 



In experiments which the author has now several times re- 

 peated, he injected blood removed from the right side of the heart of 

 an animal and therefore normally containing sugar through the 

 capillaries of the artificially inflated lungs of another; and found 

 that as long as the blood retains its fibrine, there is as much de- 

 struction of its sugar as would take place in the living animal ; but 

 that where the fibrine has been separated from the serum and 

 corpuscles, the sugar ceases to be influenced by the presence of 

 oxygen, or ceases to disappear during this process of artificial respi- 

 ration. It would hence appear, that something besides mere con- 

 tact with oxygen is requisite for the destruction of sugar. But in 

 other experiments, he has found that oxygen is nevertheless a ne- 

 cessary agent concerned in the process of transformation observed 

 during the arterialization of the blood that has not undergone spon- 

 taneous coagulation. It would therefore seem, in fact, that oxygen 

 acts secondarily on the sugar through the medium of the fibrinous 

 constituent of the blood : that it exerts some changes upon this 

 azotized principle, which are capable of inducing the metamorphosis 

 of sugar. 



If we look to the ordinary chemical bearings of saccharine matter 

 apart from the animal system, we find that an azotized substance 

 undergoing the molecular changes of decomposition, placed in con- 

 tact with sugar readily excites a process of fermentation, and con- 

 verts it by a mere alteration of the grouping of its elements into 

 another substance, one atom of sugar (C 12 H 12 O 12 ) being resolved into 

 two atoms of lactic acid (C 6 H 6 O 6 ). We also find that sugar is 

 not susceptible of oxidation except under the influence of strong 

 chemical reagents. Chemical analogy, therefore, would lead us to 

 look upon the secondary action of oxygen as the more probable pro- 

 cess of physiological destruction ; especially when we take into con- 

 sideration, that nowhere do we meet with such a constant series of 

 molecular changes taking place as amongst the azotized constituents 

 of a living animal. In the above-mentioned experiment of injecting 

 fibrinated and defibrinated blood through an artificially inflated 

 lung, when the blood is capable of undergoing the molecular changes 



2o2 



