

1920] 



MAGXESS— INTERCELLULAR SPACES 



313 



► 



for fruit under the different temperatures tested, however, clearly 

 indicate the tendency of the oxygen-carbon dioxide ratio within 

 the tissues, regardless of the fact that the absolute values may 

 vary somewhat. 



Effect of wounding 



Many references to the effect of wounding plant tissues upon 

 rate of respiration are found in the literature. Invariably wound- 

 ing of the tissue has resulted in an increased rate of respiration. 

 Gerber has found this to be true of apples, grapes, and other 

 fruits. Applemax (i) has reported the same phenomenon for 

 white potatoes. t 



A few apples were prepared for a study of the effect of wound- 

 ing upon the composition of the internal atmosphere. A thin slice 

 of the peel was removed from each end of the fruits, and they were 

 then put in storage at the various temperatures by the side of 

 whole fruits serving as checks. The data from the analyses of 

 these fruits are reported in table III. It is apparent from these 

 data that removing the epidermis greatly facilitates the entrance 

 of oxygen to the tissues, and also the escape of accumulated C0 2 . 

 It would be interesting to know to what extent increased respira- 

 tion following wounding is due to mechanically facilitating this 



gaseous exchange, and to what extent it is due to actual metabolic 

 changes in the wounded tissues. 



TABLE III 



Effect of removing peel from ends of fruits upon composition' of 



internal atmosphere 



Tempera 

 ture°C. 



I 



I 

 20 

 20 



30 

 30 



Treatment 



Number of 

 Determinations 



Percentage CO, Percentage O, Perce ^ c c0 ' 



Whole apples 

 Ends peeled 

 Whole apples 

 Ends peeled 

 Whole apples 

 Ends peeled 



3 



4 

 2 



2 



2 



2 



+0 



6.6 



1-7 

 17.8 



74 



23 -9 

 12.6 



14.6 



1S.8 



7.0 



9-9 

 1.8 



8-9 



21 .2 



17 5 

 24.8 



173 

 25 -7 

 21.5 



Variation in composition of gases 



Considerable variation occurred between individual apples or 

 potatoes held under identical conditions. This is to be expected 



