84 THE PHYSIOLOGY OF PROTEIN METABOLISM 



be given by the mouth it is quantitatively and rapidly excreted. This 

 was demonstrated by Voit (VII) many years ago in the dog, and again 

 recently by Achard and Paisseau (50 A), who gave large doses of urea 

 to a man and found that the output of nitrogen rose immediately 

 and fell just as suddenly when the urea was stopped. Rosemann (339 

 A), however, was inclined to believe, from his experiments, that a re- 

 tention of nitrogen in the form of end products could take place. His 

 investigation was carried out on a subject who could scarcely be re- 

 garded as normal and his results remain unsubstantiated. 



As already stated in an earlier section, Abderhalden thinks it highly 

 improbable that the retention occurs in the form of protein (p. 82). 

 Von Noorden also holds that so long as the nitrogen retained is small 

 in amount it is not necessarily in the form of tissue protein ; a small 

 amount of retained nitrogen may be distributed in the blood and lymph, 

 and part somewhere as reserve material. Pfliiger held (330) that if 

 there were a retention of carbon there must also be a retention of 

 nitrogen. He believed that a kind of intermediate substance was 

 formed from the protein absorbed and stored as a reserve protein, a 

 substance which was richer in carbon and poorer in nitrogen than the 

 ordinary protein found in the tissues and tissue juices. This storing 

 of material was an actual storage, i.e. it did not lead to a new formation 

 of cells, but a mere filling out of the cells already existent a physio- 

 logical hypertrophy an eutrophy as it has been called. Even the 

 activity hypertrophy has been stated not to be due to an actual in- 

 crease in the number of tissue cells, but to a mere thickening or dis- 

 tension of existent elements. 



As the result of their study of the nitrogen : phosphorus ratio in ex- 

 periments where a great retention of nitrogen had taken place Liithje 

 and Berger (268 A) came to the conclusion that part of the nitrogen was 

 certainly retained in the form of "flesh" and that the rest of it was 

 stored in the form of dead intracellular protein just like so much 

 glycogen or fat. 



Pharmacology offers examples of a similar capacity for retention. 

 Thus the retention of bromine, iodine and fluorine has been demon- 

 strated by Tappeiner and Brandl (cit. 57) and that of chlorine by Belli 

 (57). In each of these cases the retention took place in the same 

 step-like fashion characteristic of nitrogen. 



