480 LIVER. [CHAP, xxxin. 



From a careful consideration of the anatomy of the parts, we 

 should be led to look upon the liver as a large gland in which a 

 considerable quantity of a highly elaborated secretion was slowly 

 formed, and slowly transmitted in a more highly concentrated form 

 towards the intestine. The arrangement of the vasa aberrantia 

 and of the little cavities in the coats of the thick-walled ducts, the 

 abundance of vessels and lymphatics in such close proximity to the 

 ducts, and the great similarity of their disposition with that of the 

 vessels of the gall bladder, where we know absorption of fluid 

 takes place, favour the idea that important changes occur in the 

 bile after its formation by the cells of the liver. 



The liver is, therefore, a true gland consisting of a formative 

 portion and a system of excretory ducts directly continuous with 

 it. The secreting cells lie within a delicate tubular network of 

 basement membrane, through the thin walls of which they draw 

 "rom the blood the materials of their secretion. 



Quantity and Uses of the Bile. We have already considered the 

 composition and uses of the bile in Chapter XXV.; but since that 

 part of our work was published, some important results have been 

 communicated by Bidder and Schmidt, which we shall here briefly 

 allude to.* 



These excellent observers have concluded, from numerous ex- 

 periments upon different animals, that the quantity of bile secreted 

 during the twenty -four hours is much larger than had been sup- 

 posed. Cats secreted 14'5 grammes, dogs nearly 20 grammes, 

 and sheep 25 grammes, for each kilogramme (about 2 Ibs. 3 oz. 

 avoirdupois) in the weight of the animal. From these data, it 

 is of course difficult to draw a correct inference as to the quantity 

 of bile secreted by the human subject; but, from calculating from 

 these results, it has been rendered probable that an adult man 

 secretes about 54 oz. of pure bile in the twenty-four hours, and 

 this contains about 2 oz. of solid matter. This estimate is very 

 much higher than that which we have given at p. 253. 



The activity of the secretion varies greatly at different periods of 

 the day. For one or two hours after a meal, it is very small in 

 amount; but from this time it gradually increases until it attains 

 its maximum, about the fifth hour after the last meal. The 

 secretion then rapidly diminishes in quantity, until it is not more 

 than it was two hours after the meal. The gall-bladder empties 

 itself about two-and-a-half or three hours after taking food. 



* Die Verdauungssaefte imd der Stoffwechsel von Dr. F. Bidder und Dr. C. 

 Schmidt. Mitau und Leipzig, 1852. 



