308 ASSIMILATING ACTION OF LIVER. 



would appear as if the nutritive materials, in their ultimate 

 metamorphosis, resolved themselves chiefly into these two 

 excretory products. The greater part of the biliary matter 

 poured into the intestinal canal seems to be ordinarily re- 

 absorbed with the fatty matter of the food, and to be, like it, 

 carried out of the system through the lungs in the form of 

 carbonic acid and water; it being only when the bile has 

 either been formed in excessive amount, or has been pro- 

 pelled along the intestinal tube with undue activity, that it is 

 discharged in any quantity from the rectum, as in bilious 

 diarrhoea. The secreting action of the Liver, however, is by 

 no means its sole mode of influencing the composition of the 

 blood ; for it has been shown by the recent researches of 

 M. Bernard, that the blood which leaves the liver by the 

 hepatic vein contains a peculiar substance of a saccharine 

 nature, 1 which does not exist in the blood brought to the 

 organ by the portal vein. This substance appears to be 

 elaborated by the converting power- of the liver, either from 

 materials supplied by the food, or from the products of the 

 waste of the system ; and it seems to be specially destined as 

 a pabulum or fuel for the combustive process, being usually 

 eliminated from the blood in the form of carbonic acid and 

 water during its passage through the lungs, so as not to pass 

 into the systemic circulation unless either its quantity be un- 

 usually great, or its elimination be interfered with by imperfect 

 respiration. The liver seems also to form a peculiar fat, which 

 is usually consumed in the same manner ; but if the respiratory 

 process be feeble, this fat accumulates in the cells of the liver 

 itself. 



367. The Urinary excretion has for its chief purpose to 

 throw off those products, formed in a similar .manner, which 

 are highly charged with azote. The most important of its 

 ingredients, in Man and the Mammalia, is the substance termed 

 Urea, which has a crystalline form, and is very soluble in 

 water. It contains 2 equivalents of Carbon, 4 of Hydrogen, 

 2 of Azote, and 2 of Oxygen ; and it will be seen, by referring 

 to the statement formerly given of the composition of albumen 



1 This substance is spoken of by M. Bernard as sugar : it has been 

 demonstrated, however, by the recent researches of Dr. Pavy, that the 

 liver does not form sugar, but a substance that becomes sugar almost 

 immediately upon contact with albuminous matters. 



