12 BITTER PIT INVESTIGATION. 



I agree most emphatically with Mr. McAlpine, that an apple which is ripe (no starch) is past 

 the danger of pitting. I feel that I am on the point of declaring that an apple which has already 

 lost its starch (though it may not look or taste ripe) is also past the danger. 



At any rate a great majority of the clean apples received at the laboratory were already passed 

 the starch stage, though still green and unripe, and as they proved themselves practicaUy free from 

 subsequent pitting, they bear out the point raised. 



Starch metabolism and Pit are evidently closely associated. 



Consequently, it was with a good deal of confidence, that peeled apples were stained with 

 iodine for persistent patches of starch-bearing cells. It would be most interesting to know whether 

 certain cells could maintain undissolved starch grains for any length of time before showing the visible 

 lesions characteristic of Pit. An apple might be gathered clean whilst still in the starch stage. If on 

 keeping, the starch was transformed into sugar in the general mass of pulp cells, leaving actual groups 

 of cells of the dimensions of Bitter Pit areas still with unconverted starch, then that would be an early 

 indication that Pit was present. In Rome Beauties, such masses of starch-bearing cells were found, 

 though, unfortunately, the apples were actually just under suspicion of pitting from their naked eye 

 appearance (there was a suspicious dark mottling under the skin, and on peeling the areas were 

 light brown). 



No earlier cases were found, and it still remains to determine whether starch persistence can 

 be separated from the browning and sponging of Pit by any marked interval of time. 



Most of the apples I received had already lost their starch, and were already either pitted or 

 permanently clean. As previously mentioned, the decisive point in their history had passed. 



This brings one to an interesting practical point. There seems to be no doubt that apples are 

 harvested at very different times in their ripening history. The starch may or may not already have 

 been converted. The question arises whether after storage, and its effect upon the incidence of Pit, 

 can be adequately investigated without being correlated to the condition of the apple (in respect of 

 its inner metabolism) at the time of gathering. 



If the apple is gathered subsequently to the conversion of its starch and is clean, one would 

 expect any reasonable storage to be adequate. 



If on the other hand, it is gathered with starch still present, can special methods of subsequently 

 guarding it, help it to pass the critical period of starch conversion without leaving groups of cells to 

 die? 



BITTER PIT AND POISONS. 



At one stage in the investigation it was proposed to use an experimental method based upon 

 the sensitivity of the pulp cells of the apple to minute traces of metallic poisons as described by Ewart. 



It was argued that if an apple had latent Pit not yet fully developed certain groups of 

 cells, namely those which would later die and form the Pits, would perhaps, on account of a lowered 

 vitality, be more readily poisoned than their healthy neighbours. 



It was proposed to treat the surface of peeled apples with solutions of metallic poisons just 

 too dilute to kill the healthy cells, and then watch for the death of cells in certain small defined areas 

 within the following 24 to 48 hours. 



It was found, however, that the peeled apple immediately commenced to disintegrate in any 

 of these extremely dilute metallic salt solutions, which are virtually distilled water. A peeled apple 

 at once commences to fluff and shed its cells within 5-10 minutes in pure distilled water. 



This observation caused us to make a communication to the Royal Society of Victoria, based on 

 further work, questioning Ewart's experimental evidence of the susceptibilities of apples to dilute 

 poisons. 



It was argued that the removal of minute areas of cuticle practised by Ewart made the apple 

 skin permeable, and the pulp cells were then poisoned, not only by the dilute metallic salt, but also 

 by the distilled water. 



