206 BIOLOGY. [Book ii. 



and fine droplets of the same tint, which seem to be the colouring 

 matter of the bile. 



But this contribution, if it exists, is assuredly accessory, for the 

 bile is specially formed in the fine culs-de-sac or acini whence 

 go forth the biliary canals. These culs-de-sac receive thin arterial 

 ramuscules, from which their walls and the epithelial cells, which 

 clothe them, borrow the materials whidi they elaborate and 

 transform into bile. 



Between the glycogenical cells and the secretory acini of the 

 bile there is not a very intimate physiological bond. In effect 

 the blood of the vena portse is indispensable to the activity of 

 the glycogenical cells. But a ligature of this vein by no means 

 stops the biliary secretion, alimented almost exclusively by the 

 capillaries of the hepatic artei-y.^ Inversely the ligature of the 

 hepatic artery dries up the biliary secretion. 



The glycogenical formation and the biliary secretion do not 

 suffice to exhaust the functional activity of the liver. From the 

 researches of M. Mint, it results that one of the substances 

 poured out with the bile is so by an act of simple excretion. 

 We mean a ternary substance, very rich in carbon, which is 

 likewise found in the vegetal kingdom among the mushrooms. 

 This substance is cholesterine, which, among the vertebrates, 

 seems to be especially a product of disassimilation of the nervous 

 system. The venous blood returning from the brain, that of the 

 jugular vein, for instance, contains 0,801 of cholesterine, while 

 the arterial blood darted from the heart towards the encephalon, 

 that of the primitive carotid, contains only 0,774. Now this 

 excrementitial product, which can be met with, moreover, in 

 diverse secretions, is especially taken from the blood by the liver, 

 which excretes it into the biliary liquid. There is here an act of 

 simple election. The liver lets the cholesterine filter through, 

 in the same way that to certain salts, for instance the iodide of 

 potassium, it offers that free passage which it refuses to certain 

 others, notably calomel. 



' Or6, Journal de VAnatomie et de la Physiologie, Paris, 1864. 



