202 FORMATION OF SUGAR IN THE LIVER. 



its origin in the liver itself; it is produced, as a new formation, by 

 a secreting process in the tissue of the organ. 



The presence of sugar in the liver is common to all species of 

 animals, so far as is yet known. Bernard found it invariably in 

 monkeys, dogs, cats, rabbits, the horse, the ox, the goat, the sheep, 

 in birds, in reptiles, and in most kinds of fish. It was only in two 

 species of fish, viz., the eel and the ray (Mursena anguilla and Kaia 

 batis), that he sometimes failed to discover it ; but the failure in 

 these instances was apparently owing to the commencing putres- 

 cence of the tissue, by which the sugar had probably been destroyed. 

 In the fresh liver of the human subject, examined after death from 

 accidental violence, sugar was found to be present in the proportion 

 of 1.10 to 2.14 per cent, of the entire weight of the organ. 



The following list shows the average percentage of sugar present 

 in the healthy liver of man and different species of animals, accord- 

 ing to the examinations of Bernard : 



PERCENTAGE OF SUGAR IN THE LIVER. 



In man .... 1.68 In ox . . . 2.30 



" monkey . . .2.15 " horse . . .4.08 



" dog . . . . 1.69 " goat .... 3.89 



" cat . . . . 1.94 " birds . . . 1.49 



" rabbit ... 1.94 " reptiles . . . 1.04 



" sheep . . . 2.00 " fish . . . .1.45 



With regard to the nature and properties of the liver sugar, it 

 resembles very closely glucose, or the sugar of starch, the sugar of 

 honey, and the sugar of milk, though it is not absolutely identical 

 with either one of them. Its solution reduces, as we have seen, the 

 salts of copper in Trommer's test, and becomes colored brown when 

 boiled with caustic potassa. It ferments very readily, also, when 

 mixed with yeast and kept at the temperature of 70 to 100 F. 

 It is distinguished from all the other sugars, according to Bernard, 1 

 by the readiness with which it becomes decomposed in the blood 

 since cane sugar and beet root sugar, if injected into the circulation 

 of a living animal, pass through the system without sensible decom- 

 position, and are discharged unchanged with the urine ; sugar of 

 milk and glucose, if injected in moderate quantity, are decomposed 

 in the blood, but if introduced in greater abundance make their 

 appearance also in the urine; wMe_a J &oliLtiQn of liver sugar, though 

 injected in much larger quantity than either of the others, may dis- 



1 Lemons de Physiologie Experimentale. Paris, 1855, p. 213. 



