390 Atfred J. Eivart: 



morphine sulphate are relatively more poisonous to Rome Beau- 

 ties as compared with brucine nitrate than to Five Crowns. 



The sensitivity of different organisms to strychnine sulphate 

 varies greatly. Thus Andrews^ found that a concentration of 

 1 per 100,000 rapidly kills Volvo.r, whereas a concentration of 

 1 per 1,000,000 left Diatoms, Desmids, and blue green Algae 

 unaft'ected, and a solution of 1 in 250 was required to kill 

 ordinary fresh water and marine Algae. 



Acids. 



The commonest acid produced by plants apart from carbonic 

 acid is perhaps oxalic acid, but citric acid may be produced by 

 certain fungi and b}^ fruits, nitric acid may be produced by 

 nitrifying soil bacteria, and sulphuric acid by certain sulphur 

 bacteria. 



Oxalic Arid. — 



Prepared Five Crown apples.— Three and a-half days in solu- 

 tion, and examined after one week in air. 



One per lOCO. Pits 4 to 12 mm. diameter, and 3 to 6 mm. 

 deep. 



One per 10,000. Pits 3 to 8 mm. diameter, and 2 to 4 nmi. 

 deep. 



One per 100,000. Pits 1 to 4 mm. diameter, and 1 to 2 mm. 

 deep. 



One per 1.000,000. From no perceptible effect to superficial 

 browning. 



One per 10.000,000. No perceptible effect. 



Prepared Kome l^eauty. — One week in solution, and examined 

 after one week in air. 



One per 10,000. Pits 1-3 mm. deep. 



One per 100,000. From superficial browning to pits under 

 1 mm. deep. 



One per 1,000,000. From no effect to slight superficial brown- 

 ing. 



One per 5,000,000. No perceptible effect. 



1. Proc. of the Iiidiaiia Acatleiiiy of Science, 1905, p. 195. 



