n6 



BOTAMCAL GAZETTE 



[FEBRUARY 



alkali. The exact details of the method used on this material are 

 as follows. Weighed samples of F 3 were placed in 300 cc. Erlen- 

 meyer flasks, usually about 0.5 gm., and 1 per cent NaOH, free 

 from phosphorus, was then added at the rate of 100 cc. of NaOH 

 for each 1.0 gm. of substance. The flasks were stoppered and 

 placed in an electric incubator at 37-40 C, where they were allowed 





Fig. 12. — -Influence of supplementary fertilization with both K and P on heavy 

 N fertilization: no. 120, heavy N+extra K and P, cool house; no. 47, "normal" N+ 

 extra K and P, warm house; no. 55, heavy N+extra K and P, warm house; no. no, 

 "normal" N+extra K and P, cool house; note that "complete fertilizer" failed to 

 counteract effects of heavy N at higher temperature; are not growth effects noted in 

 no. 55 referable to stimulus received at time of germination ? 



to remain 48 hours. The flasks were shaken about 4 times each 

 day. At the end of the digestion period the insoluble material 

 was filtered off on ashless filter papers and carefully washed with 

 lukewarm water. The combined filtrate and washings were then 

 neutralized to litmus with acetic acid and the P0 4 ions precipitated 

 with magnesia mixture in the presence of an excess of NH 4 OH. 

 This precipitation was conducted at a low temperature, the solutions 



