198 M. M. McCooL 



CONCLUSIONS 



Pure solutions of manganese salts are extremely poisonous to pea and 

 wheat seedlings. The degree of toxicity is greatly reduced by full nutrient 

 solutions and by soil cultures. 



The injurious action of the manganese ion is manifested mainly toward 

 the tops of plants. Chlorosis of the leaves is the first indication of an 

 overdose of manganese. 



Manganese is less injurious to plants grov/n in the dark than to those 

 grown in the light. 



Calcium, potassium, sodium, and magnesium ions are each effective 

 in counteracting the poisonous action of manganese. Mutual antagonism 

 exists between the manganese ion and each of the following: potassium, 

 sodium, and magnesium. 



BIBLIOGRAPHY 



Aso, K. 



1904 On the practical application of manganous chlorid in rice- 



culture. Tokyo Imp. Univ., Agr. Col. Bui. 6:131-133. 



Bartmann, H. 



1910 Le manganese en champ d'experiences. Journ. agr. prat. 

 1910:2:666-667. 



Bertrand, G. 



1897 a Sur r intervention du manganese dans les oxydations provo- 

 quees par la laccase. Acad. Sci. Paris. Compt. rend. 124: 

 1032-1035. 

 1897 b Sur Taction oxydante des sels manganeux et sur la consti- 

 tution chimique des oxydases. Acad Sci. Paris. Compt. 

 rend. 124:1355-1358. 



1905 Sur I'emploi favorable du manganese comme engrais. Acad. 



Sci. Paris. Compt. rend. 141 : 1255-1257. 



Brenchley, W. E. 



1910 The influence of copper sulphate and manganese sulphate upon 

 the growth of barley. Ann. bot. 24:571-583. 



Coupin, H. 



1 90 1 Sur la sensibilite des vegetaux superieurs a des doses tres faibles 

 de substances toxique. Acad. Sci. Paris. Compt. rend. 132 : 

 645-647. 



