892 Alfred J. Eivart : 



The cuticle and bloom of apples is therefore as impermeable 

 to acids as it is to metallic poisons. Another point ^Yorthy of 

 note is that with the strong acid solutions, the pits are at first 

 pale in colour, the dead tissue softer and more watery, slowly 

 becoming a deeper brown on keeping in air. 



Sulphuric Acid. — 



Prepared Five Crowns. — One week in solution and three weeks 

 in air. 



One per 10,000. Pits confluent and 5 mm. deep. 



One per 100,000. Pits smaller, up to 3-4 mm. deep. 



One per 1,000,000. Pits smaller, up to 1-3 mm. deep. 



One per 50,000,000. Faint superficial browning in some cases. 



One per 500,000,000. No perceptible effect. 



Prepared Rome Beauties. — In solution one week, and examined 

 after one week in air. 



One per 10,000. Pits 1-3 mm. deep. 



One per 100,000. From superficial browning to pits 1-2 mm. 

 deep. 



One per 1,000,000. All the prepared spots browned super- 

 ficially, but no distinct pits. 



One per 10,000,000. No perceptible effect. 



After floating Rome Beauties with a good bloom and normal 

 skin on a solution of 1 per 1000 for 14 days, and then keeping 

 for two weeks in air, a few minute spots appeared on the sur- 

 face, but no pits, and the pulp remained quite sound. Evidently, 

 therefore, the normal skin of this variety is still more imper- 

 meable to sulphuric than it is to nitric acid, and the latter acid 

 being more volatile will more readily enter through the lenticels 

 without necessarily displacing the air in their pores by liquid. 

 Tliis is a point of theoretical rather than of practical impor- 

 tance, since although appreciable traces of nitric acid may be 

 present in the air after thunderstorms, they are hardly in suffi- 

 cient amount to affect apples during the time they remain present. 



The specific resistance to poisons. 



The foregoing results show clearly the extraordinary sensiti- 

 vity of the pulp cells of apples to poisons. They are in fact more 

 sensitive to poisons than any other plant or animal cells hitherto 



