INFLUENCE OF LIVER ON PROTEID METABOLISM. 903 
muscles ; and since such increased metabolism continues during some 
time, the excess proteid must be supposed to be in the first instance 
stored within them. 
The influence of assimilated proteids in increasing the metabolism of 
the tissues, and the manner in which such increased metabolism is 
brought about, has received the attention of many workers. According 
to the view held by Voit, which has been already referred to, such 
additional proteid is not built up into the bioplasm of the tissues, but 
passes into the tissues, and, by contact with the bioplasm, stimulates it 
to increased metabolism ; such metabolism occurring, according to Voit, 
entirely in the circulating proteid, and outside, in a sense, the actual 
bioplasm. On the other hand, according to the view which has been 
strenuously supported by Pfliiger, such excess of proteid is directly 
stored, not in the interstices of the bioplasm, but by being built up into 
its constitution ; so that this substance grows at the expense of any 
excess of proteid pabulum which is brought to it by the circulating 
fluid, and such growth or increased nutrition of living substance in itself 
directly promotes an increased destruction. 
That this view is, at least in part, correct, appears from the experi- 
ments by Schondorff, which were carried out under Pfliiger 's direction. 1 
Schondorff perfused blood, taken from a dog which had been kept fasting 
for some days — (1) through the limbs, and then through the liver, of a 
well-nourished dog, which had been kept chiefly upon proteid food, and 
which was killed immediately before the experiment ; (2) through the 
limbs, and then through the liver, of a dog which had been kept fasting 
for some days ; and (3) blood, which was taken from a well-nourished dog, 
was passed through the limbs and liver of a fasting animal. In five 
experiments in which blood from a fasting animal was sent through the 
organs of a well-nourished dog, the urea of the perfused blood was in- 
creased by amounts varying from about a quarter to more than double 
its original quantity. Out of five experiments, in which the blood of a 
fasting animal was sent through the organs of a fasting animal, the 
amount of urea was diminished in two by 9 "5 5 and 6 "9 per cent., while 
in three it was hardly appreciably altered. In these cases, there- 
fore, there was practically no proteid metabolism. In two experiments 
in which the blood of a well-nourished animal was sent through the 
organs of a fasting animal, the urea of the blood was diminished by 
13'5 and 144 per cent. There was therefore also here no proteid meta- 
bolism, the diminution of the urea having been probably due to diffusion 
out of the blood into the tissues. That the increase which was obtained 
by passing the blood of a fasting animal through well-nourished organs 
was not due to the diffusion of pre-existing urea from the well-nourished 
liver, was determined by a control experiment, in which it was found 
that the amount of such diffusion was at most very small. 2 
These experiments show, according to Pfliiger, 3 that the effect of increased 
proteid food has been to produce change in the bioplasm, directly causing 
this to grow and to become more active in its metabolism ; whereas, on the 
other hand, a diminution of proteid food has produced the reverse change, 
namely, diminution in amount of bioplasm, with inactivity of proteid 
1 Arch./, d. fjcs. Physiol., Bonn, 1893, Bd. liv. S. 420. 
2 The amount of urea in the blood of the starved dogs averaged 0'0348 per cent. ; the 
maximum amount in the proteid-fed dogs, - 1529 per cent. 
3 Arch.f. d. ges. Physiol., BonD, 1893, Bd. liv. S. 408. 
