386 xilfred J. Ewavt: 



more dilute solutions, symptoms of poisoning (browning of cells, 

 etc.) usually do not show until after the removal from the solu- 

 tions, and even although the apples are kept in moist air, there 

 is a possibility of some concentration taking place. This is, 

 however, just what occurs under natural conditions whenever a 

 plant absorbs any substance which it does not use, or does not 

 use as rapidly as it absorbs it, both of which cases are of common 

 occurrence in nature. In any case the artificial bitter pit tissue 

 has the same peculiar dry, corky appearance of natural bitter 

 pit, whether it is produced by poisonous heavy metals or metals 

 of the alkali and alkaline earth groups, and whether it is pro- 

 duced in a watery solution or not. Mere superficial examination 

 is siiflEicient to distinguish it from the soft brown rot produced 

 by fungi, strong doses of poison, etc. The browning of the 

 tissue, the brittle cell walls and the tendency to shrinkage and 

 cracking are not shown when the pits are produced by relatively 

 strong doses of acid, but are when very dilute solutions are used, 

 i.e., Avhen the passage from life to death is gradual instead of 

 sudden. Hence the appearance of certain features of bitter pit 

 is rather a characteristic of life than of death. If a peeled 

 apple is soaked in a solution of 1 per 100,000 of mercuric chlo- 

 ride, a brown zone travels slowly inwards, preceded by a pale 

 zone a few millimetres broad. In a 1 per 10.000 solution, the 

 pale zone is much narrower, and contains living cells at its inner 

 border, whereas in the browned tissue all are dead. The brown 

 colour is evidently not due to any ferment action, or it would 

 not be produced in the presence of mercury, l)iit is possibly tlie 

 result of the direct oxidation of a chromogen produced or liber- 

 ated during the death of the pulp cells. 



Although gold is never present in great abundance, traces of it 

 in soluble form occur in the sea, and possibly also in some soils 

 and in soil waters. 



Gold Cldoridt. — 



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

 after one week in air. 



One per 10,000. Pits 2 to 5 mm. deep. 



One per 100.000. Pits 1 to 2 mm. deep. 



One per 1,000,000. Pits superficial to 1 mm. deep. 



One per 10,00J,0C0. Superficial browning only. 



