1910.] Co7itrihutions to the Biochemistry of Growth. 311 



Table III. 



Before transplantation (9 days). 



After transplantation (15 days). 





Increase in 

 weight in 

 grammes. 



N- reten- 

 tion in 



N-rctention. 



Increase in 

 weight in 

 grammes. 



N-retention in 



N-retention. 





grammes. 



Weight increase. 



grammes. 



Weight increase. 











20 -1 (total) 

 — 5 '1 (tumour) 



0 -59 (total) 

 — 0 '12 (tumour) 



0 -023 (tumour) 



Rat I 



10 



0-37 



0 -0.37 



15-0 (host) 



25 -0 (total) 

 — 1 "5 (tumour) 



0-47 (host) 



1 -10 (total) 

 — 0 "04 (tumour) 



0 -031 (host) 

 0 "026 (tumour) 



Katll ... 



20 



0-72 



0 -036 



23 -5 (host) 



1-06 (host) 



0 -045 (host) 



Rat III... 



20 



0-64 



0-032 



10 -0 (total) 

 (No tumour) 



0 -85 (total) 

 (No tumour) 



0 -085 (total) 

 (No tumour) 



up a given weight of tumour tissue than is necessary to build ap an equal 

 weight of somatic tissue. It is worth considering whether or not this result 

 may, in itself, be an adequate explanation of the rapidity of growth of the 

 tumour cells. The significance of this fact will be discussed in greater detail 

 in a succeeding paper. 



The question arises as to the source of the supply of nitrogenous material 

 from which the tumour cells build up new tissue. We have seen already 

 that in our experiments the tumour cells did not grow at the expense of the 

 tissues of the host. They must therefore have elaborated the nitrogenous 

 material taken in as food. 



In a normal growing animal, part of the nitrogen of the food goes to repair 

 the wear and tear which the cells have undergone ; this fraction is represented 

 by the nitrogen excretion of the animal in a state of nitrogen hunger. 

 Another fraction is used for the building up of the growing tissues of the 

 animal ; this fraction is represented by the amount of nitrogen retained by 

 the animal. A third^ fraction, which has no specific function and which can 

 be replaced by fats or carbohydrates, serves as a source of energy ; this 

 fraction may vary within wide limits, and, together with the first-named 

 fraction, it is represented by the amount of nitrogen excreted in the urine in 

 an animal in a state of nitrogenous equilibrium. In the terminology of 

 Eubner, these three fractions receive the name of " repair fraction " 

 (Abniit/.ungsquote), "growth fraction " (Wachstumsquote), and " ergogenic 

 fraction " (dynamogener Verbrauch). It is obvious that a tumour growing 

 in an animal does not derive its nitrogen from the repair fraction, since this 



