146 PHYSIOLOGY CHAP. 



2. On adding a few drops of a mixture of 2-3 volumes concentrated HCL, 

 and 1 volume of dilute perchloride of iron to some cholesterol, and evaporat- 

 ing, a residue is olitained, which is at first red-violet in colour, afterwards 

 I due-violet (U. Schiff). 



XXII. Far more is known of the origin of bile salts and 

 /iif/ments (though the data are still incomplete) than of the 

 formation of the other secretory products which are poured into 

 the intestinal tube. 



The fundamental question is whether these specific constituents 

 of the bile are pre-formed in the blood, the liver only having the 

 task of eliminating them, as the kidneys eliminate the constituents 

 of urine, or whether they are exclusively formed in the liver, i.e. 

 are they specific products by external secretion of the hepatic 

 cells, and not the products by internal secretion of many or all 

 the tissues of the body. The first theory (already adumbrated 

 by Aristotle and Galen) was upheld in more recent times by 

 Morgagni, van Swieteu, and Glisson ; the second by Sanders, Job. 

 Miiller, Kunde, Moleschott. In accordance with their opposite 

 points of view, the former admit the possibilities of a haematogenous 

 as distinct from a kepatof/enous jaundice ; the latter regard 

 cholaemia and jaundice as invariably due to the reabsorption of 

 the bile formed in the liver, i.e. as being essentially hepatic in 



origin. 



Till quite lately, the arguments in favour of this last theory 

 were not adequate to solve the question : 



() The blood that supplies the liver contains (it was said) 

 neither acids nor bile pigments ; these must therefore be formed 

 in the liver. But (as Baldi pointed out) this argument loses all 

 value if we reflect that, many kilos, of blood pass through the 

 liver in the 24 hours, and that the amount of biliary products 

 the blood must contain as the equivalent of what the liver secretes 

 during the same period is excessively small, certainly less than 

 3 grins, per cent, and therefore not to be detected by the 

 chemical means at our disposal. 



(&) After extirpation of the liver in the frog (J. Miiller, Kunde, 

 Moleschott), the bile constituents do not accumulate in the blood, 

 as they do after tying the bile-duct. The frogs in which 

 Moleschott excised the liver lived 15 to 21 days, without any appear- 

 ance of cholaemia or jaundice. To this Baldi replies that the 

 metabolism of frogs is so sluggish that enough bile would not 

 collect in a few days in the blood or urine, to be detected chemi- 

 cally. In fact, when Leydeu tied the bile-duct in frogs there 

 was no sign of jaundice after 14 days. Kobner, in Heidenhain's 

 laboratory, did detect bile acids in the frog's urine, after ligation 

 of the bile-duct. But even if this argument proves that the 

 liver forms bile, it does not exclude the possibility of its formation 

 by other tissues also. 



