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 Pfltiger, 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 9'55 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.f. d. ges. 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, 0'1529 per cent. 



3 Arch.f. d. ges. PhysioL, Bonn, 1893, Bd. liv. S. 408. 



