ITS SECRETION. 81 



logical relations which have been observed by Meckel* and 

 Leidy,f show that it is, in these cells that the substances taken up 

 from the blood are elaborated into bile ; and most of the physio- 

 logical facts with which we are at present acquainted, accord with 

 this view. Miiller, and subsequently to him, Kunde,{ after 

 separating the skin of the abdomen and tying the portal vein, 

 opened the abdominal cavity of large frogs ; ligatures were applied 

 to all the points of attachment of the liver, and that organ was 

 completely extirpated ; after the operation, the animals were kept 

 in narrow, dry vessels, at a low temperature, and the blood of 

 those that were still surviving after two or three days, was collected 

 by amputating their thighs. As we are justified in concluding, 

 both from the experiments of Blondlot and from pathological 

 observations, that icterus ensues within two or three days after 

 the occlusion of the gall-ducts, we must here expect to find a very 

 large quantity of bile-pigment and cholic acid, if the formation of 

 the most essential biliary constituents take place externally to the 

 liver; but although the examination was conducted with the 

 greatest care, we could not detect, with certainty, any trace of 

 either of these substances in this blood. 



I must here remark, that at the commencement of these 

 experiments we believed that, though we could find no bile- 

 pigment, we had detected biliary acids ; but we subsequently con- 

 vinced ourselves that frogs' fat, and indeed any fat that abounds in 

 olein, yields with sugar and sulphuric acid a reaction extremely 

 similar to that of cholic acid. But after we had become acquainted 

 with this source of error, and had, as far as possible, removed the 

 fat, no trace of bile could be recognised either by Pettenkofer's 

 test or by any other means (as, for instance, the exhibition of 

 taurine, the determination of sulphur in the alcoholic extract, &c.) 



It certainly cannot be denied that after such severe operations, 

 conclusions should only be drawn with the most extreme caution ; 

 but when taken in association with the above-named histological 

 and with the physiological and pathological facts presently to be 

 mentioned, the result to which we have been led by our experi- 

 ments is deserving of a certain amount of weight. 



It is further known that the biliary secretion differs from all 

 other secretions in this respect, that it proceeds from the capillary 

 system of a vein, and that even the blood of the hepatic arterial 



* Muller's Arch. 1846. 



t American Journal of Medical Science. Jan. 1848. 

 t Diss. inaug. Berol. 1850. 

 VOL. II. 



