458 PHYSIOLOGICAL CHEMISTRY. 



VOIT'S doctrine of the circulating and tissue proteids is indeed a 

 hypothesis, but it explains in a satisfactory manner a number of 

 otherwise very intricate relations and it agrees best with the facts. 

 This theory has received further confirmation from the investiga- 

 tions of several others, as PANTJM, FALCK and FEDER, on the tem- 

 porary secretion of urea after food rich in proteids. From the 

 investigations on a dog it was found that the secretion of urea 

 increases almost immediately after a meal rich in proteids, and that 

 it reaches its maximum in about six hours, when about one half of 

 the administered proteids is secreted as the corresponding quantity 

 of urea. If we also recollect that, according to an observation of 

 SCHMIDT-MULHEIM on a dog, about 33$ of the given proteids are 

 absorbed in the first two hours after the meal and about 56$ in the 

 course of the first six hours, we may then infer that the increased 

 elimination of nitrogen after a meal is due to a metabolization of 

 the digested and absorbed proteids of the food. If we admit that 

 the destroyed proteid must have been organized, then the greatly 

 increased elimination of nitrogen after a meal rich in proteids sup- 

 poses a far more rapid and comprehensive destruction and recon- 

 struction of the tissues than has been generally admitted. 



VOIT'S theory on the different behavior of the tissue proteids 

 and the circulating proteids in the animal body seems to have 

 found support in the investigations of LUDWIG and TSCHIRJEW and 

 of FORSTER. In TSCHIRJEW'S experiments a dog was given at one 

 time boiled dog's blood, and at another time the same quantity of 

 defibrinated dog's blood was injected into a vein. In the latter case 

 the secretion of urea was very little increased, while in the former 

 case it increased proportionally to the food consumed. In FORS- 

 TER'S experiments, on the contrary, a dog was transfused with 

 defibrinated dog's blood and also with horse- or dog-blood serum. 

 After the transfusion of the blood the secretion of nitrogen was 

 somewhat greater than in starvation, but the increase was only 

 inconsiderable. In two experiments, in which 395 and 611 grms. 

 of blood were transfused, the increase was only 3.6 and 3.4 grms. 

 urea, while the proteids contained in the transfused blood corre- 

 sponded to 32 and 42 grms. urea. After the tranf usion of 522 grms. 

 of dog's-blood serum, in which the quantity of proteids corre- 

 sponded to 10.6 grms. urea, the elimination of urea was only 6.4 



