Bitter Pit in Apples. 387 



One per 100,000.000. No perceptible signs of poisoning. 



One per 1,000,000,000. No perceptible signs of poisoning. 



In the 1 per 10,000 solution the contact with organic matter 

 and the presence of light causes gold to be deposited, the liquid 

 becoming golden in reflected, and green in transmitted, light. In 

 the 1 per 100,000 the gold separates in a still finer state of 

 subdivision, the liquid becoming a clear purple colour, barely- 

 perceptible in the 1 per 1,000,000 solution. Gold is deposited 

 on the skin of an apple in a 1 per 10,000 solution, and can be 

 removed by rubbing with a cloth. In the 1 per 10,000 and the 

 1 per 100,000 solutions the prepared spots are black on the sur- 

 face, and a deeper brown than usual within. This decomposition 

 of the gold chloride at the surface may explain why the pulp 

 cells appear to be so much less sensitive to gold chloride than to 

 mercuric chloride or copper sulphate. 



The action of poisonous plant products. 



Since formaldehyde is one of the primary products of the 

 photo-synthesis of carbon dioxide, and since young apples con- 

 tain chloroplastids capable of active photo-synthesis, a fact which 

 was determined by means of the Bacterium method, the possi- 

 bility needed consideration of a self-poisoning by the continued 

 production of formaldehyde, while its polymerization to sugar 

 or starch was for some reason suppressed. 



Sound adult Scarlet Nonpareil apples, which had been for 

 three months in cool storage were floated on a 1 per cent, 

 solution (1 c.c. of 40 per cent, in 100 c.c. of water) for one week. 

 They were covered with dark, irregularly distributed sunken 

 areas, but even after three weeks the marks were superficial, and 

 did not extend into the pulp. No trace of formaldehyde could 

 be detected in them, the poison, being volatile, having long since 

 evaporated. In a 1 per 1000 solution, numerous small spots 

 appeared, and in a 1 per 10,000 a few minute ones, but these 

 were also entirely superficial. Solutions of 1 in 20,000 and 1 

 in 100,000 produced no effect. 



Formaldehyde. — 



Prepared Yates' Pippin. — ^Three days in solution, and examined 

 in three days. 



