484 OF SECRETION AND EXCRETION. 



deposited in the tissue of the liver; and we accordingly find Figuier 1 and 

 Sanson 2 arriving at the conclusion that vegetables alone are capable of pro- 

 ducing starch, a part of which, when formed, is applied by the plant to the 

 nutrition of its own tissues, whilst another part, stored up in cells, becomes 

 subservient to the nutrition of Herbivorous animals. In these again, a por- 

 tion of the starch is consumed in the vital processes, whilst another portion 

 is distributed to the tissues, being especially abundant in the liver ; and to 

 this source they believed the sugar contained in the blood of Caraivora was 

 traceable. This view, however, became untenable when it was shown that 

 in animals fed exclusively for months on ordinary butchers' meat, in which 

 no trace of starch or sugar is present, the presence of sugar in the liver, 

 though in much smaller quantity, could readily be demonstrated. In such 

 cases it was obvious that the sugar could not be derived- directly from the 

 aliment, but must have been the result of metamorphoses taking place in 

 the economy. 



397. In the meanwhile Bernard, pursuing his investigations, was struck 

 with the circumstance, that if the vessels of the Liver were thoroughly 

 cleared of Sugar by the injection of water, a fresh supply of that substance 

 could be obtained, after the lapse of a few hours, upon reiujection ; showing 

 not only that the production of sugar must be external to the vessels, and in 

 the very substance of the organ itself, but also that it is capable of taking 

 place quite independently of all vital action. From a consideration of 

 these- facts, he was led to inquire whether there might not be some sub- 

 stance formed by and pre-existent in the hepatic tissue, from the metamor- 

 phosis of which the sugar proceeded ; and he, coincidently with Heusen 3 

 and Pavy, 4 was soon successful in obtaining a peculiar substance possessing 

 properties intermediate between those of starch and dextrin, and capable, 

 under the action of ferments, of being readily converted into sugar, and of 

 ultimately undergoing alcoholic or lactic acid fermentation. This substance 

 was termed Glycogen by Bernard ; Hepatiu, or Amyloid substance, by Pavy ; 

 and Zoamyliu by Rouget. It belongs to the group of colloidal or non-diffu- 

 sible bodies (Pavy). The great influence exercised by the nature of the 

 food on its amount has been clearly shown by Dr. Pavy, 5 McDonnell, and 

 Tscheriuoff. 6 Dr. Pavy found, on analyzing. the livers of dogs fed exclu- 

 sively on animal diet, about 7 per cent, of amyloid substance; whilst in 

 those fed on meat and sugar it amounted to 14.5 per cent.; and in. those fed 

 on vegetable diet alone to 17 per cent. In cases where animals were fed on 

 starch and sugar, the livers were pale and pulpy. No, amyloid substance 

 was present in animals dying of starvation or wasting disease. 7 The amount 

 of Glycogen in the Liver of those animals in which the tissue of the organ 



1 See Gaz. Med , Gaz. Hebdomad., and C. llendus, 1867. 



2 Journ. de la Physiol., 1858, p. 244; 1839, p. 104. 



3 Archiv f. Path. Aunt , Bd. xi, p. 395. 



4 Guy's Hospital Reports, 1858, p. 291 ; 1859, p. 204; 1801; p. 197; Phil. Trans., 1800. 

 6 Phil Trans., 1800, p. 604. 



6 Sitz. d. k. Akad. zu Wien, Bd. li, 1865, p. 412. See also Dock, Pflii^er's Archiv, 

 Bd. v, p. 571. 



7 This is not in accordance with Bernard's experiments (Revue Seient., t. viii, 1872- 

 73, p. 1155) who found glycogen to be constantly present, even after prolonged fast- 

 ing. Dork states that when in consequence of inanition all glycogen had disappeared 

 frnin the liver, the ingestion of sugar into the stomach caused the appearance of large 

 quantities in the liver in the eour.-e of a few hours, but no such effect was produced 

 in rabbits by the ingestion of albumen. See Ticgel, idem, Bd. vi, p. 249. The 

 differences in the amount of glvco^en found by different observers tinder apparently 

 similar conditions may perhaps ho due to the circumstance pointed out by v. VVittieh 

 (Centralblatt f. d. Med. Wiss , 1875, p. 117), that the formation of glycogen does not 

 take place with equal energy in all parts of the liver, some producing it more abun- 

 dantly than others. 



