366 Jones and Skive.—Influence of Ammonium Sulphate 
Slight specking occurred on the leaves of the plants in some of the Totting- 
ham cultures of series F supplied with ferrous sulphate, but this was not at 
all serious, and after two weeks from the time the cultures were started it 
did not increase appreciably. 
The hydrogen-ion concentrations of the culture solutions were deter¬ 
mined at the end of each growth interval between two successive solution 
renewals. In Table IV are given the initial pH values of the culture 
solutions, the highest and lowest values obtained during the growth periods, 
and the average of all the values for each solution of the three series. 
Table IV. 
pH values of the culture solutions of the Tottingham series (E and F) and 
the ammonium-snip hate series (G) supplied with iron in the proper form 
and in sufficient amounts to prevent chlorosis. 
Tottingham series (F). 
Source of iron FePO 4 . 
Culture 
pH values. 
No. 
Ini- 
High- 
Low- 
Aver- 
Ini- 
tial. 
est. 
est. 
age. 
tial. 
T 1 R 1 C 1 
4*9 
6*2 
5* 1 
5*75 
4*9 
V 
4*9 
6-6 
5*2 
5*96 
4*9 
c 5 
4*9 
6-6 
5*2 
6-02 
4*9 
C 7 
4*9 
6-2 
5*3 
5*75 
4*9 
R 3 Ci 
4*9 
6-2 
5*3 
5-86 
4*9 
C3 
4*9 
6-6 
5*3 
5*99 
4*9 
V 
4*9 
6 -i 
5*3 
5*78 
4*9 
RsV 
4*9 
6-2 
5*2 
5*85 
4*9 
C 3 
4*9 
6-2 
5*3 
5*83 
4*9 
R 7 Ci 
4*9 
6-2 
5*3 
5‘8o 
4*9 
TgRjCi 
4*8 
6-0 
4*9 
N 
5*54 
4*8 
c 3 
4*8 
6 -i 
4*9 
5*6 1 
4*8 
c 6 
4*8 
5*8 
4*9 
5-5 1 
4*8 
R 3 Cx 
4*8 
5*8 
4*9 
5*5° 
4*8 
C 3 
4*8 
5*9 
4*9 
5*56 
4*8 
R 5 Cx 
4*8 
5*9 
4*9 
5*46 
4*8 
TsRxQ 
4*7 
5*8 
4*9 
5*4 2 
4*7 
C3 
4*7 
5*8 
4*7 
5*42 
4*7 
K3C1 
4*7 
5*8 
4'9 
5*44 
4*7 
T 7 R 1 C 1 
4*7 
5'7 
4*9 
5*38 
4*7 
Shive’s 
r 6 c 2 
Totting- 
ham’s 
T 3 R 1 C 4 
To 
bring out 
4*5 
4-6 
clearly the m 
Tottingham series (F). 
Source of iron FeSO±. 
pH values. 
High¬ 
est. 
6*4 
6-6 
6-6 
6*3 
6*4 
6*4 
6*4 
6*5 
6*5 
6*4 
6 *o 
6 *o 
5*9 
6*i 
6*2 
6 *o 
5*7 
5*7 
5*7 
Low¬ 
est. 
5*i 
5 * 2 
5*3 
5*3' 
5 * 1 
5*2 
5*3 
5*3 
5*3 
5*3 
4*9 
4*9 
4*9 
4*9 
4*9 
4*9 
4*9 
4*9 
4*9 
5*5i 
5-62 
5*59 
5*56 
5*66 
5*55 
5 H 1 
5*45 
5*4 2 
5*6 4*9 5*36 
5*7 4 * 6 5*30 
5*7 4*7 5* 2 9 
A mmonium-sulphate 
series (G). 
Aver¬ 
age. 
5*84 
5*99 
6*21 
01 
79 
°5 
06 
88 
08 
88 
Source of iron FePO±. 
pH values. 
Ini- 
High- 
Low- 
Aver- 
tial. 
est. 
est. 
age. 
4*9 
6 -o 
4*3 
5*°5 
4*9 
5*5 
4*3 
4*75 
4*9 
5*o 
4*3 
4*59 
4*9 
4*7 
4*2 
4*43 
4*9 
5*3 
4*2 
4*58 
4*9 
5* T 
4 * 1 
4*5° 
49 
4 -6 
3*8 
4* 2 4 
4*9 
4*6 
4*2 
4*33 
4*9 
4*6 
3*8 
4-18 
4*9 
4*6 
3*9 
4*34 
4*8 
4-6 
4*4 
4*52 
4*8 
4*6 
4*4 
4*53 
4-8 
4*7 
4 -i 
4*4 3 
4*8 
4*7- 
4*i 
4*4 2 
4*8 
4*6 
3*9 
4*3i 
4*8 
4*6 
4*0 
4*4° 
4*7 
4*6 
4*4 
4*52 
4*7 
4*6 
4*3 
4*49 
4*7 
4 -6 
4*3 
4*47 
4*7 
4*6 
4*4 
4*55 
change of the solutions brought about by the action of the plants during the 
intervals of contact throughout the growth period, the pH values given in 
the columns of averages in Table IV for each of the three series were plotted 
to form the graphs of Fig. 3. The data represented by these graphs were 
plotted according to the descending order of values in series E. These 
