468 



SECRETION. 



ML. 



the liver. Prepared in the way above indicated, and pulverized, it may be preserved 



for an indefinite period. 



The peculiar reaction of the glycogenic matter with 

 iodine has led to its recognition in the substance of the 

 liver-cells and in some other situations. Schiff found in 

 the liver-cells minute granulations, which presented the 

 peculiar color on the addition of iodine, characteristic of 

 glycogenic matter. Bernard, a few years after his dis- 

 covery of this principle in the liver, recognized it in cells 

 attached to the placenta. He believes that these cells 

 produce sugar during the early period of foetal life, before 

 the liver takes on this function, and that they disappear 

 during the later months, as the liver becomes fully devel- 

 oped. 



Since the discovery of the glycogenic function of the 

 liver, anatomists have found amyloid corpuscles in various 

 of the tissues of the body. We do not propose, how- 

 ever, to discuss this question in all its bearings, but only 

 to consider the known relations of the amyloid substances 

 found in the body to the formation of sugar. 



In the first place, there can be no doubt of the fact, 

 that the liver of a carnivorous animal that has been fed 

 exclusively on meat contains an amyloid substance readily 

 convertible into sugar. The question of the existence of 

 the same amyloid matter in other tissues and organs is 

 only pertinent in so far as it bears upon the production 

 of sugar or upon the formation of the glycogenic matter 

 in the liver. In no tissue or organ in the adult has it 

 been demonstrated that there is any formation of sugar, 

 except the ordinary transformation of starch into sugar 

 in the process of digestion. 



If the liver taken from an animal recently killed be 

 simply kept at about the temperature of the body, after 

 it has been drained of blood or even after it has been 

 washed through the vessels, sugar will be rapidly formed 

 in its substance. This must be due to some ferment re- 

 maining in the tissue ; and Bernard has, indeed, been able 

 to isolate a principle which exerts this influence in a 

 marked degree. If an opaline decoction of the liver be 

 allowed to stand until it has become entirely clear, show- 

 ing that all the glycogenic matter has been transformed 

 into sugar, and alcohol be added to the liquid, the hepatic 

 ferment will be precipitated. This may be redissolved 

 in water, and it effects the transformation of starch into 

 sugar with great rapidity. From these facts, it is pretty 



FIG. 139. Apparatmfor the extrac- conclusively shown that the following is the mechanism 



tion of glycogenic matter. (Ber- 



nard.) of the production of sugar in the liver : 



A B displacement apparatus in which The liver first produces a peculiar principle (analo- 



the filtration takes place; C, animal 



charcoal mixed with the decoction gous to starch in its composition and in many of its prop- 

 tion ; M/iamp-w^n^attoched' to erties, though it contains two atoms more of water) out 

 bon hr and fomfoj? auTaf^?uppar of which the su g ar is to te formed. The name glycogenic 

 part of the apparatus; I, precipita- matter may properly be applied to this substance. It is. 



ting-glass ; G. glyoogenic matter . , , . ,. 



precipitated; V, alcohol. as far as is known, produced m all classes of animals, 



