14 



injury from liigli temperature begins.* Within a few degrees 

 above freezing point respiration is no doubt very slight, and it 



m refrigerating chambers. Suitable temperatur 

 purposes have been found by experience, but moi 



lede^e of the behaviour of fruit at thesf^ ti 



time 



m 



matter 



aeration. Air should have as free access to the fruit as possible, 

 and therefore large masses of fruit should not be closely crowded 

 together. Good circulation of the air should also be kept up, 

 and for this the current of cold air from the refrigerating machine 

 may often be sufficient, but in some cases ventilating fans have 

 been used. The amount of care necessary in the matter 

 of aeration depends, of course, largely on the temperature 

 chosen for the storage chamber, as well as on the kind and 

 condition of the fruit. 



In the case of the transport of peaches in America in refrigera- 

 tor cars, injury to the fruit is stated to be common, and the 

 injury has been found to be most frequent in the central part of 

 the top tiers of boxes. Cold airt is led along the bottom of the 

 car, and, though diffusion and circulation equalise the tempera- 

 ture to some extent, it may be assumed that the upper strata of 

 air have a somewhat higher temperature than the lower, and 

 therefore that the fruit in the upper boxes respire more acti^'ely 

 than the rest. The explanation is therefore suggested^ that the 

 injury is '* due to insufficient oxygen and to an accumulation of 

 carbon dioxide within the paper wrappers in which peaches are 

 so often shipped/' The preventive would no doubt be more 

 uniform cooling, with better aeration if necessary. 



It must be remembered that active respiration means an appre- 

 ciable evolution of heat by the respiring tissues. Hence, in the 

 case of large masses of fruit, if this heat is not rapidly con- 

 ducted away, the temperature of the fruit (and of the air adjoin- 

 ing it) will rise, whereby the respiration will be further increased, 

 and so on. Such heating at '* compound interest " will be liable 



temperatu 



insufficient, and may 



lead to the loss of portions of the fruit* 



chamber, and mav 



Should the temperature in the cold storage chamber be allowed 



may be iound tha 

 o reduce the tem 



p 



shipments of bananas. § The fruit then ripens rapidly and 



spoils. 



* Pfeffer, Physiology of Plants (Eng. ed.), vol. I., p. 561. 



t From ice-bunkers. 



X (x, R. Hill, loc, cit. The injury had been described by a dealer as 

 "ice-scald/* but the peaches had probably not been in a temperature lower 

 than 7® C. (45° F.). Whole car-loads of the fruit are occasionally spoilt. 



§ When the refrigerating machine has been out of order for a time. 

 Bananas are not kept at a very low temperature during ocean transport. 

 About 7^ C. (45*^ F.) is the temperature chosen in some cases. 



