Robert A. Steinberg 367 



Burrell (4) as taking place in the stems of soybean with either calcium 

 or magnesium deficiency. Nightingale, Addoms, Robbins, and Scherm- 

 erhorn (•?/) also found little alteration in amino acid and protein con- 

 tent of tomato stems to occur with calcium deficiency. The data for 

 sulfur deficiency in stems showed more differences in all cases in regard 

 to both chemical reactions. 



The reason for the unchanged values in stems with magnesium and 

 calcium deficiency might be one of several. It may be a characteristic 

 reaction to a deprivation of these elements. A mild deficiency could also 

 possibly cause a similar condition. Further, it should be recognized that, 

 if localization of symptoms is paralleled by alterations in amino acid 

 and protein content, the stems of plants should be relatively less affected 

 than the leaves. 



Skok (43) obtained calcium deficiency symptoms with the bean plant 

 when supplied with urea as a source of nitrogen. Additional studies 

 would seem desirable, but it seems clear that nitrate reduction is not 

 a primary function of calcium, nor the inactivation of nitrate a causative 

 factor in calcium deficiency. 



The data on the effects of deficiencies in micronutrients are very few 

 (Table III). Bennett (/) reports that iron deficiency leads to an in- 

 crease in amino acid nitrogen and a decrease in protein nitrogen. Gilbert, 

 Sell, and Drosdoff (12) reported a definite increase in both constituents 

 in the leaves of tung during early stages of growth with copper defi- 

 ciency. Later stages showed a marked decrease in free amino acids, 

 however. These results may afford an explanation of those reported by 

 Lucas (24), who concluded that copper does not participate in protein 

 metabolism. The increased protein may well be due to an inhibition in 

 protein breakdown, a view in accord with that of Gregory and Sen (14) 

 that synthesis and breakdown of protein followed different paths. Cop- 

 per enzymes may play a relatively small part in the former reaction as 

 compared with the latter. 



The data of Mulder (28) on molybdenum deficiency are different for 

 leaves and stems. This author emphasizes the decrease in protein ac- 

 companying a molybdenum deficiency and the large increases in un- 

 utilizable nitrate. The leaves show a relatively lesser decrease in amino 

 acids than in protein. 

 Insufficient data on the effects of boron deficiency also do not permit 



