3 78 Alfred J. Ewart : 



at intervals of a centimerre, by means of a clean, sharp razor, 

 and to float the apples in a litre of the dilute solution to be 

 tested. Apples ahnost always float with their equatorial line 

 submerged and horizontal. Controls w^ere performed with each 

 set of experiments. It was found with practice easy to remove 

 fra<rments of the cuticle without injurinp: the cells beneath the 

 epidermis. These fragments must be quite colourless and trans- 

 parent. If they show any colour some of the subjacent cellular 

 tissue has been removed. Such apples are denoted in the fol- 

 lowing pages as "" prepared '" apples, and very close examination 

 with a lens is necessary to detect the fact that they have been 

 prepared. If kept in moist air, the prepared spots undergo no 

 change or sinking, and are unaffected even by a week's immersal 

 in pure distilled water. Occasionally, however, and particularly 

 in the case of Five Crown apples, wet rot may start at a pre- 

 pared spot, but this is quite difterent from the bitter pit change, 

 which is always ultimately characterised by dark-coloured or 

 brown, dry, more or less shrivelled cells with brittle walls, even 

 when produced by long immersal in a dilute poisonous solution. 

 The pits are, in fact, often noticeably dry when the apples 

 are taken out of the poisonous solution, and always become 

 so after it has been kept in air. In wet rot, however, whether 

 due to fungal hyphae or not, the tissue always seems to become 

 soft and watery. 



Owing to the exhaustion of the supply of unsprayed apples 

 from my own orchard, some of the later tests were performed 

 with purchased apples whose history was unknown, but which 

 had in many cases obviously been sprayed. These were cleaned 

 with a cloth and warm water, but this was not always sufficient 

 to remove the poison adhering to the skin. In such cases the 

 controls in water may show a well-developed pit under one or 

 more of the prepared spots while the others are quite unaffected, 

 and the results with increasing dilutions of poison will show 

 more or less pronounced inconsistencies. This difficulty was 

 most pronounced with the Five Crown apples, which also seem 

 to be more affected by submersal in water than the other kinds 

 used. In all such cases the experiments were repeated, and they 

 are only given when consistent results were obtained with the 

 first, second and even third trials. On this account shorter 



