312 



BOTANICAL GAZETTE 



[OCTOBER 



an increased amount of C0 2 in the tissues, without a corresponding 

 decrease in oxygen. 



Table II gives the data obtained for potatoes. The potatoes 

 used were purchased on the open market, and the variety was not 

 determined. They were sound, smooth, and of uniform average 

 size. A few carrots were also studied, for comparison with the 

 apples and potatoes. From the data presented it is apparent 

 that the same general tendency holds in potatoes and carrots 

 that was noted in apples, that is, an increasing percentage of C0 2 

 and a decreasing oxygen content at higher temperatures. 



TABLE II 

 Analyses of gas in intercellular spaces of potatoes and carrots 



Temperature of 

 storage °C 



Number of 

 determinations 



II 



22 



II 



24 



8 

 8 



2 

 2 



Percentage COa 



19.6 

 344 



12.2 

 28.6 



Percentage 3 



Potatoes 



10.9 

 5-7 



Carrots 



i3- 1 

 5-2 



Percentage 



COa + O* 



30-5 

 40. 1 



25-3 



33-8 



Percentage N 

 by difference 



69.5 



59-9 



76.7 

 66.2 



It will be noted that the total CO 



oxygen 



in the case of potatoes than was found in apples. This variation 



much 



in p 



may 



from 



apples 



It is necessary to use much larger samples of potato 



tissue in order to obtain sufficient gas for an analysis than is 

 essential when apple tissue is used. 



The amount of gas that may be coming out of solution in the 

 juice, rather than from the intercellular spaces, presents a difficulty 

 inherent in this method of sampling. There is no assurance that 

 the gas that comes out of solution is of exactly the same composition 

 as that of the intercellular spaces. The consistent results recorded 



