THE LIVER SECRETION OF BILE. 483 



of the Tunicata, announced by Dr. Schmidt, and corroborated by the ob- 

 servations of Luwig and Kolliker, 1 was considered to be only interesting 

 because it destroyed what had till then been looked upon as one of the most 

 important means of distinguishing the tissues of the animal from those of 

 the plant. In 1848, however, Bernard 2 observed, that whilst the Blood of 

 the system generally, and that of the Vena Ports; in particular, in an ani- 

 mal fed exclusively on meat, appeared to be destitute of Sugar, a very nota- 

 ble quantity could be detected in the blood of the Hepatic Vein and right 

 heart that is to say, in the blood which had passed through the Liver. He 

 immediately inferred that a new function, the formation of Sugar, was to be 

 attributed to the Liver; that the sugar so produced was thrown into the cir- 

 culation, and then, by undergoing combustion, ministered to the mainte- 

 nance of animal heat. He was supported in this view by the authority and 

 analysis of Lehmann, 3 who suggested that the Sugar might proceed from the 

 decomposition of albuminous compounds, since there was a smaller quantity 

 of albumen in Hepatic as compared with Portal Venous blood ; and there 

 were also good chemical grounds for supposing that albumen might split up 

 into nitrogenous compounds, represented by the conjugated biliary acids 

 (which also contain the sulphur), and into non-nitrogenou's compounds rep- 

 resented by Starch, Glycogeu, and Sugar. Schmidt (of Dorpat) conceived 

 that the Sugar might result from the decomposition of the fatty substances ; 

 whilst Frerichs thought that the albuminous substances might break up into 

 Glycose and Urea. Bernard 4 himself, however, was disposed to consider that 

 Bile and Sugar w r ere produced in the Liver independently of one another ; 

 first, because the formation of Sugar was most active at a much earlier 

 period after food than that of Bile ; and, secondly, because in one of the 

 Mollusca (Limax flava) he found that the liver secreted sugar and bile 

 alternately, the former during, the latter after, digestion. The observations 

 of Bernard, from their novelty and interest, attracted the attention of many 

 chemists and physiologists, and it was soon shown that sugar, though in com- 

 paratively small proportion, was frequently present in the blood of the gen- 

 eral circulation, and of the Vena Portre, as well as in that of the Hepatic 

 vein. Thus Chauveau 5 found in the arterial blood of a Horse, which had 

 fasted for six days, 0.06 per cent, of Sugar, and in the systemic venous blood, 

 0.05 per cent. Colin also detected traces of Sugar in the Chyle and Lymph. 

 Very careful investigations were made by Dr. Harley, Poiseuille, Lefort, 6 

 and others to determine the proportion of Sugar in the Liver, and in the 

 blood drawn from different parts of the body in animals under different cir- 

 cumstances, the general results of which appeared to be that sugar existed 

 in the arterial blood of the Dog in the proportion of about 1.5 per 1000; in 

 the Vena Cava inferior below the renal veins, 0.54 per 1000 ; and in .the 

 Vena Cava inferior, above the diaphragm, i.e., above the entrance of the 

 Hepatic Vein, 1.12 per 1000. In Herbivora, the quantity of Sugar in the 

 blood of the Hepatic Vein amounted to about 1 per cent, during fasting, 

 and from H to 2 per cent, at a period of full digestion, whilst the mean 

 quantity found in the liver substance was said to be from ^ to 2^ per cent. 

 The much larger proportion of sugar obtained from the liver of Herbivor- 

 ous as compared with Carnivorous animals, especially after a meal contain- 

 ing much amylaceous or saccharine material, naturally led to the supposi- 

 tion that these substances were derived from the aliment, and were merely 



1 Annales des Sciences Naturelles, 184(3. 2 Archives Gen. de Medecine. 



3 Comptes Rendus de 1'Acad. des Sciences, 1855, p. 587. 



4 L('9ons, 1854-55, p. 93 etseq., a view which has been supported on histological 

 grounds by Accolas, Thesis, Strasl>ourg. 1867. 



5 Gaz. Med , 1857; L'Union M^d., 1857. 6 Gaz. M6d., 1858. 



