FORMATION OF SUGAR IN THE LIVER. 269 



after death, its production is clearly independent of the ele- 

 ments of food. One of Bernard's experiments may be quoted 

 in proof of this : Having fed a healthy dog for many days ex- 

 clusively on flesh, he killed it, removed the liver at once, and 

 before the contained blood could have coagulated, he thor- 

 oughly washed out its tissue by passing a stream of cold water 

 through the portal vein. He continued the injection until the 

 liver was completely exsanguined, until the issuing water con- 

 tained not a trace 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 mat- 

 ter, 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-sac- 

 charine substance. This and other experiments led him and 

 others to the conclusion that the formation of the amyloid sub- 

 stance by the liver is the result of a kind of secretion or elabo- 

 ration 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 convertible into 

 sugar. The former, chiefly excrementitious, passes along the 

 bile-ducts into the intestines, where it may subserve some pur- 

 poses in relation to digestion, and is then for the most part re- 

 absorbed, and ultimately eliminated during the processes con- 

 cerned in the production 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 con- 

 sumed in the respiratory process, and thus contributes to the 

 production of animal heat. 



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

 cesses in the living body, under the control of the nervous sys- 

 tem. 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 excreted by the kidney, 

 and thus produce the leading symptom of diabetes. Section of 

 the inferior cervical ganglion of the sympathetic nerve also 

 produces diabetes. 



The channel by which the influence of the nervous system, 

 is conducted in the preceding and similar experiments is not 

 accurately known ; no theory having been permanently estab- 

 lished, which explains all the facts hitherto observed in con- 



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