360 W. E. TOTTINGHAM AND A. J. BECK 



counteracted the effect of manganese by delaying the yellowing 

 of the leaves. The different species of plants varied in their 

 response to manganese and their relief by iron. 



Fukutome,* growing flax on soil in pots, observed similar 

 beneficial antagonism between manganoas chloride and ferrous 

 sulfate. 



Kelley^ has described a chlorotic effect in pineapples grown 

 on soils rich in manganese. He attributes the trouble in large 

 part to the absorption of an excess of calcium by the plant and 

 consequent difficulty in the assimilation of phosphorus. 



The investigations here briefly reviewed suggested the pur- 

 pose of the present investigation. While it is well known that 

 manganese can not replace iron in the physiological requirements 

 of the plant it seems possible, to the contrary, that it may 

 seriously interfere with the functions of the latter element. The 

 present investigation is therefore confined to a study of the 

 effects of equimolecular proportions of manganous and ferric 

 chlorides upon the growth of wheat plants in water cultures. 

 The two concentrations employed with each salt, namely: 



M M 



and TrxTTT;^ are equivalent to about 1 part per 8000 and 



per 800,000 parts of solution respectively for manganous chlo- 

 ride (MnCls) and 1 part per 6000 and per 600,000 for ferric 

 chloride (FeCl2). These concentrations were chosen because 

 they had been found by previous investigators to lie respectively 

 in the region of distinct toxicity and in that approaching stimu- 

 lating effects alone, with reference to manganese salts. 



The study was limited to the antagonistic relations between 

 manganese and iron in the belief that the chlorotic effects due to 

 manganese might indicate interference with the role of iron in 

 the production of chlorophyll. Antagonism between these metals 

 having been demonstrated by the investigations here cited, it 

 appeared possible that the degree, if not the direction, of such 



* Fukutome, Y., On the influence of manganese salts on flax. Tokyo Coll. 

 of Agr. Bulletins 6 : 137-139, 1904. 



* Kelley, W. P., The function and distribution of manganese in plants and 

 soils. Hawaii Agr. Expt. Sta. Bulletin 26, 1912. 



