GL YCO GENESIS— THE OR Y OF BERNARD. 9 2 5 
what little there is in the blood ia 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 mauy 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 (C'entralbl. 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 cceliac plexus. The same remark applies to the results 
obtained by Morat and Dufourt by excitation of the vagus {Arch, de physiol. norm, et 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, Xasse found that liver digested 
with chloroform water has a fi'ee ainylolytic action, which must in that case be due to a 
ferment (Rostocker Ztg., 1889, No. 105). See also Salkowski, C'entralbl. f. d. Tried. 
Wissensch., Berlin, 1889, No. 13). 
4 Pavy, " Physiology of Carbohydrates," p. 134. 
