[Proc. Eoy. Soc. Victoria, 24 (N.S.), Ft II., 1911.] 



Art. XXVI. — On Bitter Pit and the Sensitivity of 

 Apples to Poisons. 



By ALFRED J. EWART, D.Sc, Ph.D., F.L.S. 



(Professor of Botany and Plant Physiolog-y in the 

 University of Melbourne). 



[Read 14th December, 1911.] 



Introduction (page 367). 



Part I. — The sensitivity of apples to poisons (page 368) ; the influence 

 of the cuticle and bloom of apples on the absorption of poison 

 (371) ; apples more sensitive than other organisms (374) ; do 

 apples accumulate and permanently retain mercury from 

 dilute solutions? (375) ; the actual sensitivity of the pulp cells 

 of apples to poison (377) ; the influence of age (382) ; bases 

 generally present in soil (384) ; the action of poisonous plant 

 products (387) ; alkaloids (388) ; acids (390) ; the specific resist- 

 ance to poisons (392) ; the influence of ionization and of the 

 respective ions (394) ; the nature of toxicity (399) ; the action 

 of gases and volative substances (400). 



Pai't II. — The problem of bitter pit (page 404) ; can surface poisoning 

 produce deep seated bitter pit tissue? (409) ; the starch grains 

 of bitter pit (410) ; the non-solution of the starch grains 

 (411) ; the source of the poisons causing bitter pit (415). 



Summary (page 417). 



Introduction. 



In the early part of the present year, Dr. White- put forward 

 as a tentative theory the suggestion that the defect known as 

 bitter pit in apples might be associated with the use of poisonous 

 spraying materials for codlin moth and other pests. She was 

 able to detect lead in the bitter pit tissue of apples from 

 orchards which had been heavily sprayed with arsenate of lead, 

 and from her study of the ferments of normal and affected 

 apples, was also led to the conclusion that the defect could only 

 be ascribed to the action of a poison. She also pointed out that 

 bitter pit appeared to be especially common on well-tended and 

 well-sprayed orchards, and was much less so on neglected 



