336 DIGESTION. 



of sugar or albumen, and until no sugar was yielded by 

 portions of the organ cut into slices and boiled in water. 

 Having thus deprived the liver of all saccharine matter, 

 he left it for twenty-four hours, and on then examining it, 

 found in its tissue a large quantity of soluble sugar, which 

 must clearly have been formed subsequently to the organ 

 being washed, and out of some previously insoluble and 

 non-saccharine substance. This and other experiments 

 led him and others to the conclusion that the formation 

 of the amyloid substance by the liver is the result of a 

 kind of secretion or elaboration out of materials in the 

 solid tissues of the gland such secretion being probably 

 effected by the hepatic cells, in which, indeed, as already 

 observed, the substance has been detected. 



According to this view, then, the liver may be regarded 

 as an organ engaged in forming two kinds of secretion, 

 namely, bile and sugar, or rather, glycogen readily con- 

 vertible into sugar. The former, chiefly excrementitious, 

 passes along the bile-ducts into the intestines, where it 

 may subserve some purposes in relation to digestion, and 

 is then for the most part re-absorbed, and ultimately 

 eliminated during the processes concerned in the produc- 

 tion of animal heat. The latter, namely sugar, being 

 soluble, is, unless Pavy's view be correct, taken up by the 

 blood in the hepatic vein, conveyed through the right side 

 of the heart to the lungs, where it is probably consumed in 

 the respiratory process, and thus contributes to the pro- 

 duction of animal heat. 



The formation of glycogen or of sugar is, like all other 

 processes in the living body, under the control of the 

 nervous system. Bernard discovered that by pricking the 

 floor of the fourth ventricle, the quantity of sugar formed 

 was so much in excess of the normal quantity, as to be ex- 

 creted by the kidney, and thus produce the leading symptom 

 of diabetes. Section of the inferior cervical ganglion of the 

 sympathetic nerve also produces diabetes. 



