SUGAR. 217 



portal and hepatic veins to give considerable probability to the 

 view,* that the sugar which is formed in the liver a fact which 

 was originally discovered by Bernard, and subsequently confirmed 

 by Frerichs (see vol. i. p. 290, and vol. ii. p. 90) owes its origin 

 to the decomposition of albuminates, and more especially of fibrin. 

 The possibility that a carbo-hydrate may be contained in albu- 

 minous substances as an intimate constituent or adjunct, as in 

 salicin, phlorhidzin, and amygdalin, was first conjectured by 

 Berzelius, and has since been clearly demonstrated by Liebig. The 

 tendency of albuminous substances to pass into the butyric fermen- 

 tation, which is especially noticed in fibrin and casein, may also, 

 perhaps, be interpreted in the same manner. Hence not merely 

 the sugar which is conveyed into the bodies of herbivorous animals 

 with the food in the form of starch, but especially that which is 

 generated in the organism itself, must possess high importance 

 in the metamorphosis of animal matter generally. It is a striking 

 fact, however, that notwithstanding this abundant supply both 

 from without and from the liver, sugar is found only in compara- 

 tively small quantities in the blood of herbivorous animals, 

 although it is present in scarcely smaller quantities in the blood of 

 the carnivora, even after the use of a purely animal diet. It is not 

 less remarkable that nature has provided the egg with a small 

 quantity of sugar, and that the amount of sugar in the hen's egg is 

 increased rather than diminished with the development of the 

 embryo. These facts undoubtedly indicate that the sugar or the 

 carbo-hydrates generally, as well as the fats, must serve some other 

 purpose than that of maintaining the heat of the animal body by 

 their simple, although gradual oxidation. It will be presently seen 

 that by these remarks we do not by any means intend to deny that 

 the development of the heat, which is generated by the consump- 

 tion of these substances, is one of the most important objects of 

 their introduction into the animal organism ; but if the sugar served 

 solely to generate heat, we can scarcely explain why the quantity 

 should increase in the egg during incubation, whereas we should 

 rather expect that it would wholly disappear during the oxidation 

 which accompanies this process of development. The question fur- 

 ther arises, why the sugar, which is certainly present in far smaller 

 quantities in the blood of the carnivora than in that of the herbi- 

 vora should not be immediately consumed in the former, and 

 rendered unamenable to our reagents, since the sugar occurring 



* Ber. d. k. sachs. Gos. d. Wiss. 1850, S. 130-146. 



