362 



W. E. TOTTINGHAM AND A. J. BECK 



then separated, dried at about 98°C. and weighed. In the few 

 cases where plants failed to develop through apparently inherent 

 unfitness such plants were rejected and correction made to the 

 basis of six plants. 



SERIES 1 



A small-berried, pure strain of spring wheat was employed in 

 this preliminary series. In figure 1 the superior development of 

 plants in the cultures on the low plane of ferric chloride supply 

 is clearly shown. The unfavorable effect of this salt on the 

 high plane, except in respect to color of the tops, is especially 

 prominent. Attention is particularly called to the prevalence 

 of the toxic effect of manganese over iron at the low plane of 

 supply. This is strikingly evident in the color of the tops. The 

 reverse, however, was the case at the high plane of supply. There 

 the influence of iron was the stronger. 



Data concerning the yields are presented in table 1. Each 

 value is the average obtained from duplicate jars. 



TABLE 1 



Yield of six wheat plants grown three weeks in nutrient solutions containing 



manganous and ferric chlorides 



o 



— fa 



Dry tops 



Weight in milligrams 



Relative to control = 100 



Dry roots 



Weight in milligrams 



Relative to control = 100 



Fresh roots 



Maximum length in millimeter 



Relative to control = 100 



305 



87 



145 

 63 



60 

 30 



From the data of table 1 it can be seen that with respect to 

 growth of roots even the low plane of manganous chloride was 

 toxic. When supplied jointly with ferric chloride it almost com- 

 pletely antagonized the latter. At the high plane of supply, on 



