[Pboo. Roy. Soc. Victoria, 26 (N.S.), Pt I., 1913]. 



Akt. 1 1. — On Bitter Pit and the Sensitivity of Apples 

 to Poison. 



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



(Prot'essor of Botany and Plant Physiology in the Melbourne University). 



[2nd Paper.] 



(With Plates III.-V.). 



[Read 13th March, 1913.] 



In the tirst papev^ a detailed account of the action of various 

 poisons on the pulp cells of apples was given, and their extreme 

 sensitivity to certain metallic poisons shown. Tliis sensitivity was 

 so great that it Avas possible to produce pitting in apples by quau- 

 ties of lead, meicui-y and copper so minute as to i)e incapable of 

 detection, even by delicate methods of technical analysis, at least 

 with the quantities of material available. 



Many points still remained open, however, both in regard to the 

 influence of external conditions upon the sensitivity of apples to 

 poison, and also in regard to the bearing of the facts observed upon 

 the problem of bitter pit. In addition. Mr. McAlpine has recently 

 published a voluminous report on bitter pit. in whith he confidently 

 assumes that l)itter pit and poisoning have no iclationsliip. 



The influence of temperature on poisoning. 



It has long been known that at low temperatures or when in cool 

 storage, the development of bitter pit is retarded, and Scott (Phyto- 

 pathology, 1911. p. 32) found the same to be the case with the 

 development of the spots, which he concluded were due to spraying 

 Avith arsenate of lead. Hence it was of interest to determine the 

 influence of temperature upon the formation of pits by direct poison- 

 ing. The method used was as previously described. A}»))les wt-re 

 Hoated each in 1 litre of the poisonous solution after removing frag- 

 ments of the cuticle of approximately a scjuare millimetre in area, 

 from points 1 or more certtimetres apart around the periphery of the 

 apple. (See table I.) 



1 I'roc. Ro.v. Soc. A'ictoria, vol. xxiv., 191-2, p. 367. 



