INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 29 
With these salts, as with the acids, the pines appeared on the whole 
more resistant to toxic action than the angiosperms present. There 
was less evidence in the experiments of a difference in susceptibility 
to salts in general between the grasses and the dicotyledons. Heald's 
tests of the resistance of corn and peas to copper salts * showed for 
these plants a reversal of their relative resistance to acid, the peas 
being able to grow in twice as strong copper solution as corn, whereas 
with four mineral acids they could grow in solutions only one-fourth 
as strong. 
Ammoniacal copper carbonate was also used with jack pine. A 
plat of this pine was given a solution made up of 0.006 ounce of 
copper carbonate and 0.099 fluid ounce of ammonia per square foot 
the first day after germination, and this was repeated two days later. 
Eight days after germination the plat was again treated, using 0.014 
ounce of carbonate and 0.22 ounce of ammonia per square foot. 
Practically all the seedlings were killed by these treatments. Most 
of the injury appeared to be done by the first two applications, in 
which a total of 0.012 ounce of carbonate per square foot was ap- 
plied. This plat, which received a total of 0.026 ounce of copper 
carbonate, was resown 16 days after the last application. No serious 
injury occurred to the second sowing. 
Another plat treated just before sowing (plat 60, Table VI) fur- 
ther indicated a very great toxicity for ammoniacal copper carbonate 
if only the amount of copper contained is considered. The injury 
to pine in this plat was much more severe than in plat 64, which had 
been treated with sulphuric acid more than 25 times the weight of 
the copper carbonate used on plat 60. It is probable that the 
extremely toxic action of this fungicide was due more to the action of 
the ammonia than to the copper. The known tendency of ammonia 
to prevent the precipitation of copper salts from solution may, how- 
ever, result in more prolonged activity of the copper in this disin- 
fectant than when simple aqueous solutions of copper salts are applied 
to the soil. 
FORMALIN. 
Like mercuric chlorid, formalin is capable of killing seed outright 
if applied at the time of sowing. In a test of yellow pine in which 
the disinfectant was applied at sowing (plat 415, Table VI) most of 
the seeds were killed before they gave any outward evidence of 
commencing to germinate. So far as could be learned, those which 
were able to start germination were uninjured. In plat 416 (Table 
VI), which received the same amount of formalin, half at the time 
of sowing and half at an interval of a month earlier, no injury could 
be detected. In all other cases, formalin was applied several days 
iHeald, F. D. Op. cit., p. 152. 
