262 DIGESTION. [CHAP. xxv. 



addition of the tartrate of potass and copper causes a precipitation 

 of the brown oxide of copper. Yeast added to it at a certain tem- 

 perature causes fermentation ; and alcohol may be obtained from 

 the fermented fluid by distillation. 



There can be no doubt, then, that sugar is formed in the capil- 

 laries of the liver independently of the food ; it is equally certain 

 that fat is separated at the same point, for it appears in the hepatic 

 cells ; this, too, is doubtless the result of chemical changes in the 

 hepatic circulation, independent of the food, because we find good 

 grounds for concluding that the fat of the food, emulsified by the 

 pancreatic fluid, is absorbed by the villi, and does not reach the 

 liver. 



Thus are formed in the laboratory of the liver these two products 

 fat and sugar, very nearly allied in chemical constitution. The 

 former is carried into the intestine with the bile, and there ab- 

 sorbed, with the fat of the food, by the villi. The latter is carried 

 by the hepatic veins to the right side of the heart, and thence to 

 the lungs ; and both appear to be formed by the liver, whether 

 they have existed in the food or not. 



What, then, it may be asked, can be the object of the formation 

 of these products by the liver ? If it be to feed the calorifacient 

 process, then the additional question arises, why should each pass 

 to the right side of the heart by a different route ? 



It seems to us that there is in these arrangements distinct in- 

 dication of a provision for the slow and gradual transmission to the 

 lungs of these carbonaceous elements ; in order to guard against the 

 blood in these organs becoming surcharged by them so as to inter- 

 fere with the due introduction of oxygen. 



It seems necessary for health that the blood should be supplied, 

 on the one hand, duly, but gradually^ with carbonaceous matters, 

 such as sugar and fat, and, on the other hand, with oxygen ; when 

 the former elements are deficient, fever is the result, the elements of 

 the tissues are consumed by the devouring element, oxygen ; and 

 hence it is that we often see such striking results from the gradual 

 introduction of alcohol, or other carbonaceous matters, into the 

 system ; but when the latter element is deficient, the great vital 

 changes of the blood are delayed, or suspended, and death rapidly 

 ensues. And in the various diseased states of the body there 

 are infinite shades of difference, as regards the supply or the defect 

 of these great elements ; either too much carbon or two much 

 oxygen ; or the one is normal in amount, while the other is deficient. 

 A common result of the too ready assimilation of carbonaceous 



