[Proc. Kot. Soc. Victoria, 26 (N.S.), Pt. II., 19U]. 



Akt. XVJI, — Oti Bitter Pit and Sensitivity to Poiaons. 



By ALFRED J. EWART, D.Sc. ; Ph.D. 

 (Professor of Botany and Plant Physiology in the University of Melbourne). 



[3rd Papeh]. 



(With Plate XXIII.) 



[Read 11th September, 1913]. 



In pursuance of foi'mer papers in Avliicli the extreme sensitivity 

 of apples to poisons was described, it was thought desirable to 

 obtain a comparison with some other plant structure also capable 

 of prolonged semi-dormant existence. For this purpose potato3s 

 were selected, which, like apples, became discoloui-ed by oxidase 

 action when dead, but which, unlike apples, are capable of further 

 growth, and can, for instance, form cork across a cut surface, 

 which apples can not do. 



In addition Rothera and Greenwoudi have recently attempted 

 to gain direct evidence in regard to the poisoning theory of Bitter 

 Pit, and with negative results. Their works and methods ap- 

 peared to demand further experimental investigation. 



Sensitivity of Potatoes to Poisons. 



In order to compare the sensitivity of apples and potatoes to 

 poisons, a number of experiments were performed of which the re- 

 sults are given below. The potatoes were prepared by removing 

 small areas of the skin, and then immersing them in the poisonous 

 solution. They were then cut in two, and tlie deptli to which 

 tho l)r<i\vn ov purple colour was developed bcneatli the pi'epared 

 spots was noted after a few hours' exposuie to moist air to allow 

 of the complete oxidation of dead tissues. SnowHake potatoes were 

 used thioughout. 



MERCURIC CHLORIDE. FIVE DAYS IN ONE LITRE OF SOLUTION, 

 TEMPERATURE AVERAGING IL^C. 



1. Chemical iiivestitfation in connection with Hitter Pit, li>13. 



