Bitter Fit in Apples. 



]7 



PREPARED YATES PIPPEN. ALL AT 12-13'C. FOR 1 WEEK IN 

 2()0 CO. MERCURIC CHLORIDE. 



1 per KRi.OOO. 



In watery - Pits 2-5 mm. 



solution. diameter and 



2-3 mm. deep. 



In well - Slight super- 

 washed and ticial brown- 

 sterilized ing to pits 

 1U% gela- 1 mm. diam- 

 tine. eter and 



depth. 



I per 1,000,00(1 



Pits 2-3 mm. 

 diameter and 

 1-3 mm. deep. 



1 per 10,0110,000 



NoHj,<:i-J 



From faint super- -No signs of 

 ficial browning to poisoning, 

 pits 1 mm. diam- 

 eter ami depth. 



From no signs - From no signs - Fromnosigns 



of poisoning of poisoning to of poisoning 



to slight slight superfic- to slight 



superficial ial browning. superficial 



browning. browning. 



At iirst sight this experiment would seem to show that tlie con- 

 veyance of poisons to the prepared spots took phice mainly by con- 

 vection and mixing movements, although the cylinders containing 

 licjuid were not disturljed, and were kept free from vibrations^ 

 and kept at as unifoi'in a temperature as possible. Mercuric 

 chloride, however, coagulates gelatine in the presence of sodium 

 chloride, and although no salt was present, the mercury evidently 

 enters into combination with the gelatine, just as mercuric nitrate 

 will precipitate gelatine by itself, so that the diffusion of the mer- 

 cury is either stopped or very greatly retarded. 



Hence to obtain a true diffusion comparison, agar and suljjhuric 

 acid were used. These do not enter into combination; the sulphuric- 

 acid diffuses as rapidly through agar as in stationary water, and 

 the agar when well washed exercises no poisonous action on the pulp 

 cells of prepared apples, while it has also the advantage of standing 

 high temperatures better without liquefying. 



Both the water cylinders and the agar cylinders were kept free 

 from disturbance or vibration, the temperatures were kept as- 

 uniform as possible, the apples Avere picked Yates' Pippins all 15 

 centimetres diameter, and each with 15 prepared spots of 1 square 

 millimetre area, equidistant around the periphery. The 1 per 

 10,000 solution contained 1.8 grams of pure concentrated sulphric 

 acid to 9999 cubic centimetres of water, or to 9999 cc. of H per cent, 

 agar solution; 150 cc. being used to each apple. 



3 



