384 Alfred J, Ewart : 



The starch grains are deposited at a later period and then 

 dissolved during ripening. 



Bases generally present in soils. 



Although the foregoing metallic poisons are found in certain 

 soils they are usually of limited occurrence, although in the 

 soils of orchards that have been frequently and freely sprayed 

 with poisonous metallic compounds, appreciable quantities may 

 be retained in the soil. As is well known, fertile soils have a 

 pronounced retentive action upon many metallic poisons, and 

 particularly those which like mercury combine with organic 

 matter (proteids, etc.). 'Nevertheless an abundant but feebly 

 poisonous base can exercise the same effect as a scarce but 

 highly poisonous one if absorbed in sufficient amount. 



The bases used were magnesium, calcium, barium and potas- 

 sium, as the sulphates and chlorates. 



Magnesium Sulphate. — 



Prepared Five Crowns. — Immersed three and a-half days in 

 solution, and examined after 14 days in air. 



One per 1000. Pits 3-12 mm. diameter : 2-5 mm. deep. 



One per 10,000. Pits 2-5 mm. diameter ; 2-3 mm. deep. 



One per 100,000. Pits 2-3 mm. diameter; 1-2 mm. deep 



One per 1,000,000. Slight superficial browning only. 



One per 10,000,000. No perceptible poisoning effect. 



Zinc sulphate gave practically identical results, except that 

 the poisoning effect was more distinct with 1 per 1,000,000, 

 and was perceptible in this dilution even with Rome Beauties. 



This sensitivity was quite unexpected in the case of mag- 

 nesium sulphate, but the apples were purchased ones of unknown 

 history, and Five Crowns appear to be somewhat sensitive to 

 prolonged immersal in water. Another batch, however, gave 

 closely similar results, but other varieties were much less sen- 

 sitive. 



Prepared Rome Beauties. — One week in solution and examined 

 after one week in air. 



One per 1000. From superficial browning to pits 2 mm. deep. 



One per 10,000. From superficial browning to pit? 0.5 mm. 

 deep. 



