400 Alfred J. Eivavt: 



cell, the presence of both outside the cell approximates more 

 closely to a physiologically balanced solution, and produces less 

 protoplasmic disturbances than when one alone is present outside 

 the cell. Taking as a definition of a toxic substance that it is 

 one which in relatively small amounts injures or kills the cells in 

 detail, or the living organism as a whole, all such substances 

 may be termed toxic so far as apples are concerned, indepen- 

 dently of what the details of their action may be. 



Taking the poisonous dose of mercuric chloride as compared 

 with the body weight of a man to be 1 per 100,000, the pulp 

 cells of apples are certainly 100, and possibly much more than 

 1000, times as sensitive as man, comparing the quantity re- 

 quired to poison a given amount of material. With alkaloids 

 the reverse is the case. Curiously enough, formaldehyde is less 

 poisonous to apples than almost any other substance tried, and is 

 certainly far less relatively poisonous to apples than it is to ani- 

 mals. No evidence of any polymerization could be detected, so 

 that evidently the adult pulp cells have developed a special 

 resistance to a substance which they themselves produce when 

 young and assimilating. 



The action of gases and volatile substances. 



The possibility of poisons in volatile form reaching apples 

 needs consideration, and accordingly a variety of substances 

 more or less likely to be present in air were tried. 



Ammonia. — Strong ammonia vapour rapidly blackens the 

 skin of sound Jonathan apples, more dilute vapours brown the 

 surface of Jonathans and Sturmer Pippin, and produce small pits 

 within three days, mainly beneath breathing pores. For quan- 

 titative estimation of the toxicity, solutions of ammonia (0.88 

 sp. gr.) in varying amounts of water were used. Thus with 

 Jonathan with a sound, uninjured skin after 1 week in 1 c.c. of 

 0.88 in 200 cc. of water, within a week numerous brown spots 

 1-5 mm. diameter, and from superficial to 3-4 mm. deep 

 appeared, but in a litre of 1 per 2000 cc, no spots or pits 

 formed even after one week's immersal and five weeks in air. 



Prepared Jonathans. — One week in solution, and examined 

 one week after removal from solution. 



