278 HAKD-BOOK OF PHYSIOLOGY. 



carbon, hydrogen, and other elements of bile will purify it, as in extra- 

 uterine life it is purified by the separation of carbonic acid and water at 

 the lungs. 



The evident disposal of the foetal bile by excretion, makes it highly 

 probable that the bile in extra-uterine life is also, at least in part, destined 

 to be discharged as excrementitious. The analysis of the faeces of both 

 children and adults shows that (except when rapidly discharged in pur- 

 gation) they contain very little of the bile secreted, probably not more 

 than one-sixteenth part of its weight, and that this portion includes 

 chiefly its coloring, and some of its fatty matters, and to only a very 

 slight degree, its salts, almost all of which have been re-absorbed from 

 the intestines into the blood. 



The elementary composition of bile salts shows, however, such a pre- 

 ponderance of carbon and hydrogen, that probably, after absorption, it 

 combines with oxygen, and is excreted in the form of carbonic acid and 

 water. The change after birth, from the direct to the indirect mode of 

 excretion of the bile, may, with much probability, be connected with a 

 purpose in relation to the development of heat. The temperature of the 

 foetus is maintained by that of the parent, and needs no source of heat 

 within itself; but, in extra-uterine life, there is (as one may say) a waste 

 of material for heat when any excretion is discharged unoxidized; the 

 carbon and hydrogen of the bilin, therefore, instead of being ejected in 

 the faeces, are re-absorbed, in order that they may be combined with 

 oxygen, and that in the combination heat may be generated. 



A substance, which has been discovered in the faeces, and named ster- 

 corin is closely allied to cholesterin; and it has been suggested that while 

 one great function of the liver is to excrete cholesterin from the blood, as 

 the kidney excretes urea, the stercorin of faeces is the modified form in 

 which cholesterin finally leaves the body. Ten grains and a half of ster- 

 corin are excreted daily (A. Flint). 



From the peculiar manner in which the liver is supplied with much 

 of the blood that flows through it, it is probable that this organ is excre- 

 tory, not only for such hydro-carbonaceous matters as may need expulsion 

 from any portion of the blood, but that it serves for the direct purification 

 of the stream which, arriving by the portal vein, has just gathered up 

 various substances in its course through the digestive organs substances 

 which may need to be expelled, almost immediately after their absorption.- 

 For it is easily conceivable that many things may be taken up during 

 digestion, which not only are unfit for purposes of nutrition, but which 

 would be positively injurious if allowed to mingle with the general mass 

 of the blood. The liver, therefore, may be supposed placed in the only 

 road by which such matters can pass unchanged into the general current, 

 jealously to guard against their further progress, and turn them back 

 again into an excretory channel. The frequency with which metallic 



