404 



USES OF THE LIVER-DUCTLESS GLANDS. 



by the form of its crystals. They are rectangular or rhomboidal, very thin 

 and transparent, of variable size, with distinct and generally regular borders, 

 and frequently arranged in layers, with the borders of the lower strata show- 

 ing through those which are super- 

 imposed. The plates of cholesterine 

 are often marked by a cleavage at 

 one corner, the lines running par- 

 allel to the borders. Frequently the 

 plates are rectangular, and some- 

 times they are almost lozenge-shaped. 

 Crystals of cholesterine melt at 293 

 Fahr. (145 C.), but they are formed 

 again when the temperature falls be- 

 low that point. 



The proportion of cholesterine in 

 the bile is not very large. In the 

 table, it is estimated at 0-62 to 2-66 



^.m.-Cholesterine extracted from the bile. partg per thousand< In a gingle ex _ 



amination of the human bile, the proportion was 0-618 of a part per thou- 

 sand (Flint). 



The origin and destination of cholesterine involve an office of the liver 

 which has not been generally recognized by physiologists ; and these questions 

 will be considered specially, under the head of the excretory action of the 

 liver. 



BiliruUn. The coloring matter of the bile, bilirubin (C 32 H3 6 N 4 6 ), 

 bears a certain resemblance to the coloring matter of the blood and is sup- 

 posed to be formed from it in the liver. It gives to the bile its peculiar tint 

 and has the property of coloring the tissues with which it comes in contact. 

 Whenever the flow of bile is obstructed for any considerable time, the color- 

 ing matter is absorbed by the blood and can be readily detected in the serum 

 and in the urine. It also colors the skin and the conjunctiva. It is soluble 

 in chloroform, by which it is distinguished from biliverdine, and forms sol- 

 uble combinations with alkalies, in which form it is thought to exist in the 

 bile. It probably is formed in the liver from the haemoglobine of the red 

 blood-corpuscles. When exposed to the air or to the influence of certain ox- 

 idizing agents, it assumes a greenish color and is changed into biliverdine. 

 It is unnecessary to follow the various other changes produced by spontane- 

 ous decomposition or by the action of reagents. 



Tests for Bile. A simple test for bile-pigment is the following : A thin 

 stratum of the liquid to be tested is placed upon a white surface, as a porce- 

 lain plate, and to this is added a drop of nitroso-nitric acid. If the coloring 

 matter of the bile be present, a play of colors will be observed surrounding 

 the drop of acid. The color will rapidly change from green to blue, red, 

 orange, purple and finally to yellow. This test is applicable only to the col 

 oring matter and does not detect the biliary salts. 



A very delicate test for the biliary salts in a clear solution not contain^ 



