30 BITTER PIT INVESTIGATION. 



VII. THE EFFECT OF DRY AND SATURATED MOIST AIR ON 

 DETACHED AND GROWING APPLES. 



It is an undoubted fact that the pitted pulp-cells contain less moisture than the adjoining 

 healthy cells. They are dry and shrivelled compared with the distended cells of the normal tissue. 

 This loss of water can either be accounted for by greater transpiration in these particular cells or by a 

 deficiency in the water-supply. 



In order to throw light on this phase of the question, experiments were conducted with apples 

 still growing on the tree and apples detached, both being kept in air saturated with moisture, and in 

 dry air. It is well known that dry air encourages transpiration, while moist air retards it, and if the 

 loss of moisture in the pitted cells was due to greater transpiration, then the apples kept in dry air 

 would be expected to develop a greater proportion of Pit. 



(a) DETACHED APPLES. 



Experiments with clean detached apples were carried out independently by Dr. Rothera and 

 myself, and the comparative results are instructive. The apples were all taken from the same tree 

 of the Annie Elizabeth variety, which had already produced badly pitted fruit. 



TABLE XVI. AMOUNT OF PIT DEVELOPED IN DETACHED APPLES IN DRY AND MOIST 



AlE RESPECTIVELY . 



Test. Commencement. Duration. Temperature. No. of Apples. Pitted. 



Dry Air . . 7th January 29 days 79-87 F. 20 1 Apple 



Moist Air . . 79-83 F. 24 3 Apples 



(Rothera 1) 



Dry Air . . 8th February 28 days 83-85 F. 18 2 Apples 



Moist Air . . 80-83 F. 18 1 Apple 



(Rothera 2) 



Dry Air . . 21st April 44 days 54-55 F.(June) 8 



Moist Air . . 81 Apple 



(McAlpine) 



With the comparatively small number of apples tested and the slight amount of Pit developed 

 there was no striking difference between them. Two apples at the most were pitted in dry air, and 

 three in moist air, so that there is no particular advantages shown one way or the other. 



In order to make the test decisive, it would be necessary to experiment with a much larger 

 number of susceptible apples, and to have them X-rayed at the outset so as to determine those which 

 were already pitted without showing any visible sign. 



It is worthy of note that the apples kept in moist air were juicy and crisp, and almost as good 

 as when picked, while those in dry air were shrivelled in the skin and tough. This justifies the advice 

 given in Report I., that when apples were kept in an ordinary store-room the air should not be too 

 dry. 



(6) GROWING APPLES. 



This experiment was carried out to test the effect of keeping apples on the tree, constantly 

 in an atmosphere saturated with moisture during the growing period, as compared with others on the 

 same tree growing naturally. Under such conditions the transpiration is considered to be reduced 

 to a minimum, and the effect on the growth of the apple and on the development of Bitter Pit was 

 noted. 



