Bitter Pit. 347 



in moist air and examined by the members of thu committee. The 

 average temperature was IS^-lSo C. Dr. Rothera brought Graven- 

 stein apples for testing. I preferred Yates' Pippin, which is a 

 hard-fleshed, resistant apple, much less sensitive to poisons but 

 always unaffected by distilled water if properly prepared. 

 The results of the test are as follows : — 



Series A. — Yates' Pippin. 



Controls. 



Di stilled water. 



(1) No pits, browning or signs of poisoning on any of the pre- 

 pared spots. 



(2) No pits, browning or signs of poisoning on any of the pre- 

 pared spots. 



Copper Sulphate. 



(3) 1 per 100,000. Well-defined brown pits 1-2 mm. deep on all 

 prepared spots. 



Lead Nitrate. 



(4) 1 per 100,000. Doubtful. i 



Mercuric Chloride. 



(5) 1 per 10,000. Large pits 1-3 mm. deep. 



(6) 1 per 100,000. Small brown pits 1-2 mm. deep on all the 

 prepared spots. 



(7) 1 per 1,000.000. Doul)tfnl.i 



Series B. — All Gravenstein apples except in the case of 6 (b), 8 (b), 

 9 (b) and 10 (b). wliere Yates apples were used. 



Coiitroh. 

 Distilled irater. 



(1) No browning, pits or signs of poisoning on any of the pre- 

 pared spots. 



(2) Light brown irregidar pits beneath three contiguous prepared 

 spots, possibly over a slightly bruised area, the other nine spots 

 quite unaffected. 



1. I could see distinct signs of poisonin{f on these apples, but as Dr. Rothera could not, they 

 are given as doubtful. Lead nitrate rapidly destroys oxidase and penetrates slowly. Lead nitrate 

 pits are always pale, copper sulphate ones much dai-ker. 



