140 BOTANICAL GAZETTE [AuGusT 
tions indicated in the preceding table. The amount of growth 
for periods of twenty-four hours was noted. 
In the solutions which contained 5; and zg}yq molecule 
per liter no growth whatever was observed, and at the end of the 
experiment the root tips were generally quite soft and flexible 
and in most cases showed a faint greenish coloration. In the 
next dilution, »;4,, molecule, a very slight growth was observed 
for the first twenty-four hours but for the second twenty-four 
hours no growth whatever, and at the end of the experiment 
these roots were also soft and flexible and colored greenish. In 
the two next dilutions ;,1,, molecule and ;y3!;9y molecule, the 
growth was considerable, but it was much greater in the later 
solution showing that the growth was retarded toa considerable 
extent by the ;,4,, molecule solution. In the sz$o0 molecule, 
CuSO, solution no growth resulted for the second twenty-four 
hours, but this is not strange since in the others the growth was 
retarded to a considerable extent. Then the ;;$00 molecule 
solution may be considered as the strength of the copper salts 
which will barely permit the roots to live. 
A series of experiments similar to the above were also pet 
formed with seedlings of Zea Mais with the following results: 
ZEA MAIS. 
n rn ie 
1 ber ; a 
Sea sop 8400 TE800 25600 51200 ogg ce 
wt ° mol. mol, — c 
Ist 24h mm 165°" 
Cuso, } 4 hours} ...., hee mm 2.5 fi 
2d 24 hours; .... se nk hy 
CuCl, Shes ed ee 2s 1.25 | Ee 
2d 25 hours! ..., Ce eae on 75 
Cu(C,H bs ee, eee eeees 2 a: 14 “ 
(C,H30,), a 24h, es a a 
bepumermprasammeccmimccnm see Tt [—_—_ oo 
. the 
Pie since the experiments with the acids showed that e 
seedlings of Zea Mais were able to withstand a greater ees 
was thought that they would likewise withstand a greatet ge a 
show" 
of copper. For this reason only the first three dilutions 
