OSTERHOUT: THE NUCLEUS AS A CENTER OF OXIDATION 343 



Warburg^" found that it was possible to isolate the nuclei from 

 erythrocytes of birds (by freezing and thawing) and that such nuclei 

 consumed oxygen about as rapidly as the normal cells. While this 

 indicates that the nucleus is the principal agent in oxidation other 

 experiments of Warburg have been interpreted to indicate that oxida- 

 tion is practically confined to the surface of the cell.^^ In these experi- 

 ments^^ it was found that NaOH greatly increased oxidation in the 

 sea-urchin egg but did not penetrate sufficiently to cause a change of 

 color in eggs stained with neutral red. In a later paper R. Lillie^^ 

 comes to the conclusion that rapid oxidation occurs at the surface 

 of the cell as well as at the surface of the nucleus. This conclusion 

 is based upon a study of the indophenol reaction in the corpuscles of 

 frog's blood. 



The use of the indophenol reaction may encounter an objection on 

 the ground that the result may depend to a considerable extent on the 

 manner in which the reagent penetrates. If the oxidizing substances 

 of the cell are largely concentrated in the nucleus those which are 

 present in the cytoplasm will first meet the reagent at the cell surface 

 and may produce at that point a deposit of granules of indophenol. 

 In the same manner the oxidizing substances which are retained 

 within the nucleus will first meet the reagent at the surface of the 

 nucleus and produce a deposit in that region. 



If, therefore, the indophenol reaction shows a higher oxidative 

 activity in the nucleus it may doubtless be depended on, since its 

 error presumably lies in the opposite direction. But if it indicates a 

 marked oxidative activity at the surface of the cell (or at internal 

 surfaces, including that of the nucleus) we must be cautious in drawing 

 conclusions. 



It would seem that more reliable evidence can be obtained by 

 investigating cases where it is not necessary that the reagent should 

 penetrate from without owing to the fact that the cell itself produces 

 substances which become colored on oxidation. 



The writer has investigated a case of this kind. The plant chosen 

 was the Indian Pipe, Monotropa uniflora, which is extremely well suited 

 to such investigations because the colorless cells contain a chromo- 

 gen which oxidizes and darkens very rapidly upon injury. An addi- 



'" Warburg, O. Zeit. f. physiol. chem. 70: 413. 1910-11. 



^1 This interpretation is by no means necessary. Cf. Loeb and Wasteneys, 

 Jour, of Biochemistry 14: 459. 1913; 21:153. 1915; also, Osterhout, ibid. 19: 335. 

 1914. Owing to the buffer action of protoplasm and to the presence of pigment 

 the penetration of a small amount of alkali is not easily detected. 



'^ Warburg, O. Zeit. f. physiol. chem. 66: 305. 1910. Biochem. Zeit. 29: 

 414. 1910. 



^' Jour, of Biol. Chem. 15: 237. 1913. 



