656 PRACTICE OF PHYSIC. 



the eyes. This yellow colour may occur from different causes ; 

 but in the jaundice, hereafter to be more exactly characterized, 

 I judge it to depend upon a quantity of bile present in the mass 

 of blood ; and which, thrown out upon the surface, gives its own 

 proper colour to the skin and eyes. 



MDCCCXVII. That the disease depends upon this, we 

 know particularly and certainly from the causes by which it is 

 produced. In order to explain these, I must observe, that bile 

 does not exist in its proper form in the mass of blood, and can- 

 not appear in this form till it has passed the secretory organ of 

 the liver. The bile therefore cannot appear in the mass of blood, 

 or upon the surface of the body, that is, produce jaundice from 

 any interruption of its secretion; and, accordingly, if jaundice 

 does appear, it must be in consequence of the bile, after it had 

 been secerned, being again taken into the blood-vessels. 



This may happen in two ways ; either by an interruption of 

 its excretion, that is, of its passage into the duodenum, which, 

 by accumulating it in the biliary vessels, may give occasion to 

 its passing again into the blood-vessels ; or it may pass into these, 

 by its being absorbed from the alimentary canal, when it hap- 

 pens to be accumulated there in an unusual quantity. How far 

 the latter cause can take place, or in what circumstances it does 

 occur, I cannot clearly ascertain, and I apprehend that jaundice 

 is seldom produced in that manner. 



MDCCCXVIII. The former cause of stopped excretion may 

 be understood more clearly ; and we have very certain proof of 

 its being the ordinary, and indeed almost the universal cause of 

 this disease. Upon this subject it will be obvious, that the in- 

 terrupted excretion of the bile must depend upon an obstruction 

 of the ductus communis choledochus ; the most common cause 

 of which is a biliary concretion formed in the gall-bladder, and 

 from thence fallen down into the ductus communis, it being at 

 the same time of such a size as not to pass readily through that 

 duct into the duodenum. This duct may likewise be obstruct- 

 ed by a spasmodic constriction affecting it : and such spasm may 

 happen either in the duct itself, which we suppose to be con- 

 tractile, or in the duodenum pressing the sides of the duct close 

 together ; or, lastly, the duct may be obstructed by a tumour 



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