SCHREINER & SKINNER: EFFECT OF GUANIDIN ON PLANTS 543 
in the light of the previously observed beneficial effect of nitrate 
in conjunction with harmful compounds,* that the entire experi- 
ment was repeated, and it gave absolutely the same results. 
The plants grew from March 17 to March 29. Again the 
effect of the guanidin did not appear until about five days had 
elapsed, and again it showed itself first, and later most marked, 
in the high nitrate solutions. Again the no nitrate cultures were 
left practically unharmed. The total green weight for the normal 
set was 163.9 grams, and in the guanidin set it was 116.3 grams, 
a relative green weight of 71. The weights of the tops in the 
different nitrate series are given in TABLE II, the arrangement being 
TABLE II 
EFFECT OF GUANIDIN ON GROWTH AS INFLUENCED BY NITRATE 
NH, as nitrate in Green weight of cultures, grams hela lisurouth. 
Culture series fertilizer mixture, De os) Comeel == 200 
parts per million Without guanidin With guanidin 
66 80 2.201 1.003 46 
55-05 72 4.040 2.040 50 
45-64 64 7.275 4.021 55 
36-63 56 10.359 57 
28-62 48 13.387 7-544 56 
21-61 40 17.394 10.110 58 
15-60 32 20.821 13.204 63 
10-59 24 22.769 16.952 74 
6-58 16 25.614 18.141 q1 
Ko 8 24.007 33.112 81 
I-56 0 15.969 16.164 100 
exactly the same as in TABLE I. The last column, giving the 
relative green weight of the different nitrate series, again shows 
the greater harmfulness of the guanidin in the series containing 
nitrate, which is especially marked in those high in nitrate. 
In the first experiment the solutions were also analyzed for 
Phosphate, nitrate, and potash. The results show a marked de- 
crease in the absorption of the nutrient salts on the part of the 
guanidin plants, although the roots themselves were not notice- 
ably affected, as is apparent from the plants visible in FIG. I and 2. 
The total phosphate, nitrate, and potash removed by the 
normal plants was diets milligrams, against only 1,088.5 milli- 
© Gillin, O., and Reed, H. S. The power of sodium nitrate and calcium 
Carbonate to decrease toxicity in see with plants growing in solution cultures. 
Jour. Amer. Chem. Soc. 30: 185. 1908.—Schreiner, O., and Skinner, J. J. . Some 
3 
effects of a harmful organic soil constituent. Bot. Gaz. §0: 161. I9T0. 
