BIO-CHEMICAL RESEARCHES ON BITTER PIT. 1 



dealt with, the evidence points to the conclusion that the initiatory stage of the disease begins on the 

 tree and afterwards develops further in store. (Figs. 3 and 4.) 



The results were so promising from the use of the X-rays that it seemed desirable to 

 test a larger number, and instead of being taken directly from the tree, fruit was used which had 

 been kept in cold storage for a considerable time. An Annie Elizabeth tree was selected, of which 

 fully 50 per cent, of the fruit was pitted, and on 27th January I picked a case of clean apples, about 

 three-fourths grown. It was placed in the Government Cool Store on 10th February, where it was 

 kept at a temperature of 30-32 degrees Fahr. At the end of three months 36 of these apples, without 

 any visible sign of Bitter Pit, were submitted to the X-rays by Dr. Herman Lawrence, of Melbourne. 

 Three of these apples (Nos. 13, 14 and 15) showed distinct signs of Bitter Pit internally, and the whole 

 were kept in my office for future examination. At the beginning of June, when kept for about three 

 weeks, they were carefully examined, and all were found perfectly free from Pit, with the exception 

 of the three above-mentioned, which were badly pitted as shown in Fig. 5. These were again sub- 

 mitted to a similar degree of X-rays, and a comparison instituted between the visibly clean specimens 

 and the same after Bitter Pit had developed in an unmistakable manner (Figs. 5, 6, 7.). 



The apples were finally examined towards the end of July. They were still fresh-looking 

 and sound, but slightly shrivelled, and only one had rotted, which was covered with " blue mould." 



The presence of Bitter Pit can thus be revealed by means of the X-rays, even although there is 

 no visible external sign of it, and in the case of experiments where it is necessary for decisive results 

 that apparently clean apples should afterwards develop Bitter Pit, this will enable us to select the 

 fruit suitable for the purpose in view. 



II. BIO-CHEMICAL RESEARCHES ON BITTER PIT. 



A. C. H. ROTHERA, D.Sc., M.A., M.R.C.S., WITH THE CO-OPERATION OF L. C. JACKSON, M.Sc., 



AND H. KINCAID, D.Sc. 



The investigation was undertaken with certain definite points in view. These were to deter- 

 mine, if possible, whether the condition of Bitter Pit could arise de novo in apples removed from the 

 tree in an apparent state of cleanness, or whether it was present, though latent, in all those apples, 

 which though apparently clean when gathered, subsequently pitted. 



At the same time, and as a part of the above problem, attention was directed to the conditions 

 which might influence the appearance of Pit in gathered apples, and also to tests which might permit 

 of the detection of the disease before any actual brown areas were detectable. 



Incidentally, interest in the theory advanced by Drs. A. J. Ewart and Jean White, that Pit 

 is due to metallic poisoning of certain groups of cells in the highly-susceptible apple pulp, compelled 

 some work of a subsidiary character to be undertaken. 



It is well-known that apples may be gathered from an orchard in an apparently clean condition, 

 and subsequently develop the characteristic lesions of Bitter Pit. 



McAlpine has shown that apparently clean apples may be maintained in that condition by 

 holding at a steady temperature of 32 F. This is probably the usual phenomenon of arrest due to the 

 great slowing up of all vital activity. There is nothing to indicate that there is any permanent in- 

 fluence on the incidence of the disease. When the low temperatures are discontinued, and the apples 

 again exposed to ordinary conditions, the apples which then develop Pit may be those predestined to 

 the condition when they left the tree. 



The evidence which I have to bring forward is mainly statistical. It has been my experience, 

 that in spite of the varying conditions, under which apples have been kept in the laboratory, that 

 either the apples as received were good, and remained good, or were from the outset marked as a 

 bad lot. 



