9 2 



Scientific Proceedings (28). 



underwent the change into adenoma when implanted beneath the 

 skin, the epithelial cells must have arisen from elements present 

 in the graft. The original tumor had been kept and sections 

 were made from different parts of it in an endeavor to dis- 

 cover undoubted evidences of epithelial proliferation. Such evi- 

 dences were found in several places, but notably in one place, in 

 the glandular tubules or epithelium-lined spaces of the seminal 

 vesicle in which organ the tumor developed originally. Hence 

 there is no longer any doubt of the existence of a carcinomatous 

 element in the original growth although it was restrained by the 

 other and less highly organized parts of the tumor. The carcino- 

 matous elements gradually gained supremacy in one strain of the 

 tumor, then in other strains, until now all the strains which have 

 been kept alive have either gone over into adenoma or are well 

 advanced in this transformation. 



54 (3io) 

 On nucleic acids. 



By JOHN A. MANDEL, W. A. JACOBS and P. A. LEVENE. 



\From the Rockefeller Institute for Medical Research^ 



In recent years, several substances have been obtained which 

 resemble one another in the fact that all of them contain in their 

 molecules phosphoric acid and a sugar, but which differ one from 

 another in the number and in the character of the nitrogenous 

 radicals contained in their molecules. To this group of substances 

 belong : (1) glucophosphoric acid ; (2) inosinic acid and guanylic 

 acid ; (3) yeast nucleic and triticonucleic acid ; and (4) thymo- 

 nucleic acid. 



All these substances may be classified as nucleic acids : 



1. The first substance is a glucophosphoric acid proper. 



2. Inosinic and guanylic acids are monopurin-glucophosphoric 

 acids. Each of them contains in its molecule only one purin base 

 besides the glucophosphoric acid. 



3. Yeast and triticonucleic acids each contains two purin and 

 one pyrimidin radical in its molecule and may be regarded as di- 

 purin-monopyrimidin-glycophosphoric acid. 



