540 BOTANICAL GAZETTE [November 



for the inorganic elements present in the seeds, because the total 

 phosphorus alone is 4.0 and 4.60 per cent respectively for the two 

 species. This discrepancy is due perhaps to the loss of nitrates and 

 part of the sodium, potassium, etc., in burning in the electric 

 muffle. In the following analysis of the inorganic elements acid 

 digestion (concentrated H 2 SO., + concentrated HN0 3 ) was used for 

 the kations and alkaline fusion for the anions. The potassium 

 was determined directly in the presence of all other elements ex- 

 cept ammonia (NH 4 — ion) and strong acid, as K 2 NaCO (N0 2 )6 — \ 

 H 2 (11). Magnesium was estimated by the volumetric method 

 as NH 4 MgAs0 4 (7). The percentage of inorganic elements is as 



follows: 



Inorganic salts (A retrojkxus); 191 7 seeds 



Percentage Percentage 



Silica 0.42 0.40 



MA+FA 0.53 0.56 



CaO 0.54 0.53 



MgO 0.82 0.84 



k;0 0.38 0.35 



Na 2 no determination 



CI Trace Trace 



S0 3 o . 34 o . 33 



P 2 O s 8.90 8.85 



N2O3 (nitrates) 0.12 ' 0.123 



Total (not including Na 2 0) 12 .05 11 .98 



Discussion 



In spite of the inaccuracy of Boutin's method for the determina- 

 tion of the nitrates, his results are probably not far from correct. 

 He stated his results in percentage of KN0 3 as shown in the 

 second column of table XI. I have calculated these as percentage 

 of N0 3 , as shown in the third column. His percentages of nitrates 

 are not far from those found by me for the stems (8.57 per cent) 

 and branches (12.50 per cent) of A. rctrojlexus, July 8 collection, 

 as shown in table II. 



Percentage Percentage 



KNO equivalent 



in NO 



A. retroflexus 22.77 x 3-9 2 



A. blitum 11.68 7.17 



A. ruber 16.0 9.82 



