314 



Messrs. W. Cramer and H, Pringle. [Jan. 25, 



observations and conclusions are intentionally restricted to animals bearing 

 tumours large enough to reveal any specific property or function of which the 

 cells of a malignant new growth may be possessed, but not so large as ta 

 introduce secondary factors due merely to the excessive size of the tumours. 



One other point must be noted, namely, the relation of the nitrogen 

 retention to increase in weight of the somatic tissue of the host after trans- 

 plantation (see Table III). In the case of the animal bearing a rapidly 

 growing tumour (Kat I), this relation is the same after transplantation as it 

 was before transplantation. In Rat III, however, when the initial prolifera- 

 tion had been followed by absorption, a remarkable change has taken place : 

 the quotient is more than twice as high after transplantation as it was 

 before transplantation. In other words, nitrogen had Jjeen retained out of 

 proportion to the increase in weight. It might be suggested that some of the 

 tissues of this animal had been so changed in composition that they contained 

 more nitrogen after transplantation. This explanation is not a very plausible 

 one, and the analysis of the various tissues, which will be given in the 

 succeeding paper, show that it cannot be maintained, since the nitrogen 

 percentage of the various tissues of Eat III agrees with the nitrogen percentage 

 of the tissues of Rat I and Rat II. 



It is only possible to explain this phenomenon by the assumption that a 

 formation of nitrogenous tissue has taken place, while at the same time non- 

 nitrogenous tissue (fat or glycogen) has been used up. Whether tliis process 

 stands in any relation to the absorption of tumour tissue and the effects produced 

 by such an aljsorption (immunisation), will have to be determined by further 

 investigations. The marked constitutional changes which accompany and follow 

 the absorption of a tumour leave little doubt that the metabolism of the animal 

 is deeply affected by this process. It is suggestive to find that in Rat II, 

 where there was apparently a concomitant absorption of the tumoui-, a sliglit 

 increase in the (juotient is found. 



Sumvmry. 



The main i(!sult of these experiments is to bo found in the following 

 facts : — 



1. Less nitrogen is necessary to build up a certain weight of tumour tissue 

 than is necessary to Iiuild uj) an equal weight of the somatic tissues of the 

 host. 



2. Animals bearing tumours maintain their positive nitrogen balance, and 

 the nitrogen retention actually increases with tlie size of the tumour. 



3. In our experiments the cells of the new growth derived their nitrogenous 

 material necessary for tlic building up of new tissue l)y it si)aring action on 



