56 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9 
depress root development as much as it does that of the tops. It is in- 
teresting to note the poor root development in 0.0005 N ferric nitrate. 
There is little difference in the relative growth with either salt in 0.001 N 
and 0.002 N. It is singular that ferric nitrate should begin to depress 
growth before it supplies sufficient iron for normal growth. 
'on 
Hsq, 
HfVO^ 
0.007 N. 0.000 O.OOOdN O.OOI&N Q.QooQM 
0.0005 
Fig. 3. Relative growth and the H-ion concentration upon the addition of acids and 
aluminum salts to solution "A." The H-ion concentration is given for the initial solution 
and at the end of the first and last weeks of growth. 
Table 3. The Ej[iect of Acids and Aluminum Salts in Solution " 
Sol. "A" 
plus 
Nor- 
mality 
Rel. Weight 
Rel. 
Transpir- 
ation 
Ini- 
tial 
pH 
After Growth 
Tops 
Roots 
1st wk. 
4th wk. 
0.00 
100% 
100% 
100% 
4.8 
6 
6.4 
(lo.i gm.) 
(0.24 gm.) 
(560 cc.) 
H2SO4 
0.0005 
95 
105 
89 
3-6 
5-4 
6 
.001 
77 
73 
75 
3-3 
■4 
6 
HNO3 
.0005 
87 
77 
89 
3-4 
4.8 
6.2 
.001 
45 
38 
53 
3-2 
3.6 
5-2 
HQ 
.0005 
90 
100 
84 
3-5 
5-2 
6.2 
.001 
46 
38 
44 
3.2 
3-6 
4.8 
Al2(S04)3...- 
.0004 
98 
93 
89 
3-9 
6 
6.2 
.0008 
87 
81 
83 
3-7 
5-2 
6.2 
.0016 
65 
69 
82 
3.4 
5 
5-2 
A1(N03)3.' .' '. 
.0008 
91 
89 
85 
3.9 
5-2 
6.4 
A1C13 
.0008 
93 
98 
88 
3.8 
5-6 
6.2 
