450 PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



subject of glycogeny — by Chavaux and Lepine.* Ac- 

 cording to these authors, the pancreas, like the liver, is 

 both a ducted and a ductless gland. As a ducted gland 

 it pours its digestive secretion into the intestines; as a 

 ductless gland it pours into the blood a peculiar fer- 

 ment, which has the property of changing liver sugar in 

 such wise that it is more readily combustible, and which 

 is therefore called glycolytic ferment. With the failure 

 of this function of the pancreas the sugar is not burned, 

 and must therefore be excreted by the kidneys. 



It seems almost certain, then, that the cause of dia- 

 betes is either the failure of the liver to form glycogen 

 (by dehydration and arrestation of sugar in the case of 

 amyloids, and by splitting in the case of albuminoids), 

 or else it is the failure of the pancreas to secrete a 

 glycolytic ferment necessary for combustion of sugar 

 in the blood. 



COMPARATIVE MORPHOLOGY AND PHYSIOLOGY OF 

 THE LIVER. 



We have already spoken briefly of the liver in con- 

 nection with the digestive organs and functions of dif- 

 ferent animals, and little more need be said here. Its 

 position, shape, and even color is similar in all verte- 

 brates, and its function is doubtless the same in all. It 

 remains a very large and important organ in inverte- 

 brates even down very low in the scale. It is nearly 

 always distinguishable by its dark color. 



As to glycogeny, this function is still performed by 

 the liver, yet glycogen is found somewhat widely dif- 

 fused in the tissues of many invertebrates, especially 

 mollusks. It is significant that the same is true of the 

 embryos of higher animals. This is exactly in accord- 



Rev. Sci., li, 376, 1893. 



