BIO-CHEMICAL RESEARCHES ON BITTER PIT. 13 



Ewart subsequently convinced us, and a small committee (Dr. Osborne and Dr. Hall), that if 

 only the very outermost layer of the skin is removed, i.e., only the cuticle, then the entry of distilled 

 water is apparently controlled, and not sufficiently rapid to injure the pulp cells beneath the denuded 

 area. The question, however, merits further work, for the metallic poison probably commences 

 by killing the epidermal cells, and the subsequent injury to the pulp cells may then all the same be 

 due to a combined action of poison and distilled water. Ewart admits the injury which distilled water 

 may produce, and does produce, should anything more than just the cuticle of the apple skin be 

 removed by the razor. 



Again, in the experiments as carried out with the careful technique suggested by Ewart, we 

 would suggest that the metallic salt acts as catalyst to the cell oxidase thus facilitating the browning 

 of the cells, which is really the chief thing to be seen. 

 The natural questions the onlooker asks are : 



(1) Is the condition produced identical with Bitter Pit ? 



(2) If so, what evidence is there to connect the death of cells as found in Bitter Pit with 



the death of cells produced by metallic poisoning ? 



To make the poisoning theory applicable to the widely distributed disease of Bitter Pit, it is 

 necessary to postulate absorption by the roots. 



It becomes necessary to show that poison absorbed in this way does produce the localised 

 lesions characteristic of Pit. 



EXPERIMENTS WITH HALF-GROWN APPLES. 



These apples were gathered with about one foot of the branch upon which they were growing. 

 They were Esopus Spitzenburg, from a Box Hill orchard. 



There were two apples to each branch. 



On 27th November they were placed with the stalk in the following solutions, and left in front 

 of a window with north aspect. 



(1) Water containing a little Eosine. 



(2) Distilled water. 



(3) Distilled water + 1 in 150,000 Copper Sulphate. 



(4) Distilled water + 1 in 600,000 Copper Sulphate. 



(5) Nutrient Solution. 



(6) Nutrient Solution + 1 in 200,OOOJCopper^Sulphate. 



(7) Nutrient Solution + 1 in 600,000 Copper Sulphate. 



(8) Nutrient Solution + 1 in 100,000 Mercuric Chloride. 



(9) Nutrient Solution + 1 in 500,000 Mercuric Chloride. 



(1) WAS A CONTROL. By 30th November Eosine was visible under the skin of one of the 

 apples on the branch, and on 6th December it was found in the flesh (in the veins), chiefly around 

 the core of the other. Therefore there is every reason to assume that in the other experiments the 

 poisonous solutions were also absorbed. 



On 6th December all apples were examined. None of them showed any signs of Pit. In some 

 cases they were commencing to shrivel, notably in (5), due to the nutrient solution having fallen to a 

 level which no longer covered the stalk. This was not at once detected, so that the apple branch was 

 for a time deprived of fluid. 



In (8) and (9) the apples were remarkably firm, with no signs of shrivelling. 



On 14th December the apples were again examined. The shrivelling was more marked than 

 on the 6th. No signs of any localised lesions were seen, several of the apples were cut, but showed no 

 indication of pitting. 



The rest were kept under examination for a time, but ultimately rotted or became too shrivelled 

 to be of any further interest. The experiment remained negative. 



