404 BOTANICAL GAZETTE | DECEMBER 
for the first time in this paper. An apparent but not real dis- 
crepancy arises from the fact that, in considering the two acids, 
the other authors have estimated the normal solution upon the 
basis of hydrogen present, whereas in mine, it is on the basis of 
the whole molecule. In view of this it will be seen that our 
results agree in making H ions as toxic in one acid as in the 
other and that about equal to the action of CN ions. It should 
be also noticed that their results represent strengths in which the 
plants would just grow, and mine a strength in which they would 
just not grow. 
In general the fungi are far more resistant to action of these 
salts than are the higher plants. The authors quoted find copper 
approximately thirty-two times as toxic as hydrogen. _ My 
results show it sixty-four times as toxic for the fungi. The 
results with Pisum show Hg to be four times as toxic as copper 
ions, while with Zea and Lupinus the copper is twice as toxic as 
the Hg ion. The fungi show Hg twice as toxic as Cu. They 
show Cu to be about four times as toxic on Lupinus and Zea as 
are H or Cuions. It would be interesting to know whether the 
HCN dissociated would be one half as strong as Cu, as would 
seem probable from theory. 
TABLE XXIII. 
SHOWING RATIO OF TOXIC ACTION. 
Pisum Zea Lupinus | Uromyces 
We oe ee ea eS Sa ic2 at 1:2 
ice igi eae eee ee ee eee 134 1:32 1:4 1: 64 
a ree 1:16 1:16 1:2 |1:128 
A ae 
These results, and others along this line, are collated in 
table XXIII, in which hydrogen, both on account of its low 
atomic weight and its low toxic effect, is taken as a standard and 
the toxic action of other ions with various plants are represented 
as ratios. 
It has been suggested that the toxic action may be some 
