CHEMICAL 311 



"Hopkins has reported the analyses of cowpea plants for total 

 nitrogen with and without inoculation. The nodules, root, and tops 

 were analyzed separately, as will be seen by reference to Table VI. 



TABLE VI. NITROGEN FIXATION BY COWPEAS: RESULTS OBTAINED 

 BY HOPKINS. (EXPRESSED IN MGS.) 



Nitrogen 

 Treatment. Tops. Roots.' Nodules. fixed. 



Ten plants with bacteria . . . 146 9 11 125 



Ten plants without bacteria 38 3 



Ten plants with bacteria ... 171 10 18 140 



Ten plants without bacteria 55 4 



Ten plants with bacteria ... 143 8 17 124 



Ten plants without bacteria 40 4 



The inoculated plants contained a much greater percentage of 

 nitrogen than the uninoculated, the average content of the inoculated 

 being 4.24 per cent, in the tops, 1.48 per cent, in the roots, and 5.92 

 per cent, in the nodules, while the average content of the uninoculated 

 was 2.48 per cent, in the tops and 0.88 per cent, in the roots. 



"The ash and the ash constituents of the nodules and the roots 

 of lupines have been determined by Stoklasa, as presented in 

 Table VII. The total ash of the nodules was found to be 6.32 per 

 cent., while that of the roots was found to be 4.55 per cent. 



TABLE VII. ASH CONSTITUENTS IN LUPINE NODULES AND ROOTS: 

 RESULTS OBTAINED BY STOKLASA. (EXPRESSED IN PERCENTAGE.) 



Constituents. Nodules. Roots. 



Si 1.59 1.90 



S 4.90 6.38 



P 6.51 4.28 



K 17.31 12.05 



Na 16.94 19.94 



Mg . . 7.41 7.05 



Ca 7.64 12.04 



Fe 0.83 0.75 



"The analyses of red-clover nodules show a potassium content 

 of 2.63 per cent, in the dry matter. The nodules, therefore, are 

 relatively rich in mineral elements as well as nitrogen compounds; 

 and Stoklasa's results (See Table VII) show that the chief differences 

 between the roots and the nodules in the composition of the ash 

 constituents are in phosphorus, potassium, calcium, and sodium. 

 The nodules are richer in the first two elements and the roots in the 

 latter two. 



" In brief, the chemical data which have been considered, although 

 small in amount, show the relative richness in nitrogen of the 

 nodule as compared with other parts of the plant. They point to 

 the accumulation of nitrogen in the seeds, at the expense of the other 

 parts, as the plant matures. That the nitrogen exists in the form 



