GL YCO GENESIS THE OR Y OF BERNARD. 9 2 5 



what little there is in the blood is in the white corpuscles a property 

 they share with most other protoplasmic structures. It is therefore 

 natural to conclude, even if we cannot show the fact conclusively 

 by analysis, that it passes from the liver to the muscles in the form of 

 grape-sugar. The extra amount of sugar in the hepatic blood might be 

 so small as easily to fall within the limits of experimental error, and 

 yet sufficient to transport a very large amount of carbohydrate in the 

 course of twenty-four hours. 1 Nor can it be said that we have any 

 means of exactly estimating the amount of sugar in the blood at all. 

 What has been estimated hitherto in the blood is not sugar alone, but 

 substances which reduce cupric salts. That a part of these substances 

 consists of glucose, is shown by the reaction with phenylhydrazine. 

 But it must not be forgotten that there occur in the blood other 

 substances which, although not glucose, also reduce metallic salts ; nor 

 can we say what proportion these hold to the glucose in the blood. 

 Hence any mere determinations of the reducing substances do not give 

 us a direct measure of the amount of glucose, and it is impossible to 

 admit as proven any theory which is entirely built up upon observations 

 of the amount of reduction yielded by the blood, on the assumption that 

 such reduction is exclusively produced by glucose. If, therefore, we 

 accept Bernard's theory, it must be understood that the evidence in its 

 favour is mainly of an indirect character. There exists an analogy in 

 the case of plants, in which the stored insoluble carbohydrate (starch) is 

 conveyed from one part to another in the form of soluble sugars. And 

 it must further be looked upon as a powerful argument in favour of 

 Bernard's hypothesis, that under certain circumstances there is rapidly 

 produced a very appreciable transformation of the liver glycogen into 

 dextrose. This occurs as the result of stimulation of almost any sensory 

 nerve, as the result of interference with the hepatic circulation, 2 and as 

 the result of administration of many drugs. And it also occurs, as was 

 found by Bernard early in his investigation of the subject, very rapidly 

 after death, especially if the liver be kept at the body temperature. On 

 the other hand, this transformation can be prevented by subjecting the 

 liver, immediately after the animal is killed, to a sufficient amount of 

 heat, as by throwing it in pieces into boiling water, or of cold, as by 

 ice-cold salt solution, 3 or by a freezing mixture. 4 It has been held 

 that this transformation, which occurs during the " survival " of the 

 liver cells, is due to a continuance of such chemical processes as occur 

 in the cells during life, and which lead to the change of their glycogen 

 into sugar, just as the chemical changes which occur in muscle which is 

 passing into rigor are generally similar to those produced during the 



1 Foster, "Text-Book of Physiology," 1889, pt. 2, 5th edition, p. 726. 



2 For these reasons conclusions should be drawn very cautiously from such experiments 

 as those of the brothers Cavazzani (Centralbl. f. Physiol., Leipzig u. Wien, 1894, Bd. viii. 

 S. 33), who obtained disappearance of glycogen in the liver, and increase of sugar in the 

 hepatic blood, on stimulation of the coeliac plexus. The same remark applies to the results 

 obtained by Morat and Dufourt by excitation of the vagus (Arch, de physiol. norm, ct path., 

 Paris, 1894, pp. 631 and 371). 



3 Dastre states that a temperature of 55 C. is sufficient to destroy the amylolytic action, 

 and that prolonged exposure to ice-cold salt solution has the same effect. He argues 

 from this that the action is not that of a ferment, but of cell protoplasm (Arch, de physiol. 

 norm, et path., Paris, 1888, p. 69). On the other hand, Nasse found that liver digested 

 with chloroform water has a free amylolytic action, which must in that case be due to a 

 ferment (Rostocker Ztg., 1889, No. 105). See also Salkowski, Centralbl. f. d. mcd. 



Wissensch., Berlin, 1889, No. 13). 



4 Pavy, " Physiology of Carbohydrates," p. 134. 



