576 Brenchley.—The Influence of Copper Sulphate and 
plants were allowed to grow on for seven or eight weeks. The series was 
very good, but even here the plants showed great individuality, as is seen 
in Table I, the variation from the mean being as much as 30% to 40 % in 
some cases. The curve of the means (Curve 3) shows that 1 : 50,000 C.S. to 
1: 250,000 C.S. practically checked growth in nearly every case, 1: 500,000 C.S. 
marking the critical point after which growth progressed rapidly. A pos¬ 
sible stimulus is indicated with 1:5,000,000 C.S., but with such large variations 
it was recognized that this might easily be due to experimental error. To 
2. 
3- 
4- 
5* 
6. 
7* 
8. 
9- 
1. 
Gram. 
Gram. 
Gram. 
Gram. 
Gram. 
Gram. 
Gram. 
Gram. 
Gram. 
A 
.123 
• 132 
•135 
* I 75 
•416 
•965 
.476 
•74 7 
•324 
B 
• 100 
.105 
•076 
• 107 
•389 
•758 
1-018 
•7 87 
•987 
C 
• 106 
•092 
• 102 
•137 
•5 66 
•732 
• 8oo 
• 761 
.818 
D 
.132 
.083 
.150 
• 109 
•641 
• 901 
•795 
•932 
•77 r 
E 
.097 
•098 
• 112 
•196 
•659 
•73<5 
.767 
•759 
•958 
F 
• 102 
— 
• 106 
•113 
.283 
•529 
•662 
• 718 
•884 
G 
• IIO 
— 
•099 
• 290 
•239 
•921 
.632 
1.030 
•984 
H 
•0S3 
— 
•096 
.304 
•447 
• 718 
• 718 
•832 
•869 
I 
• hi 
— 
•145 
• 162 
•344 
• 762 
•960 
•7 93 
.501 
K 
•088 
— 
•099 
• 210 
•337 
.318 
•698 
•672 
•958 
L 
•073 
• 102 
.107 
.183 
•408 
•886 
1.236 
.442 
•283 
M 
.089 
• 114 
•080 
•*57 
•33 1 
•901 
•984 
•839 
•936 
N 
.105 
• hi 
•*47 
•355 
•375 
1-104 
1-088 
•928 
1-029 
O 
.118 
• hi 
•145 
• u 7 
•472 
•734 
•980 
•833 
1.074 
P 
-116 
•082 
• 112 
• 189 
•323 
•183 
•883 
•868 
•916 
Q 
.105 
• 129 
•131 
• 146 
• 716 
1-182 
1*261 
•932 
1-033 
R 
.104 
.079 
• 116 
.152 
• 126 
1.039 
•95 1 
•844 
I* 120 
S 
•085 
•IOI 
• 114 
•295 
•164 
•i93 
•899 
•837 
1-114 
T 
.179 
• 120 
.168 
• 268 
•547 
•9°7 
1-061 
.976 
I-2II 
U 
• 124 
• 123 
•086 
•234 
.321 
•598 
•854 
1.025 
•670 
Mean. 
• 107 
• IO5 
• 116 
•*94 
• 4°5 
•753 
.881 
j>. 
00 
•872 
Table I. Actual dry weights of twenty series of barley plants, A-U, grown in varying strengths 
of copper sulphate with nutrient salts. The mean dry weight for each concentration of the toxic 
salt is also given. 
2. 1 : 50,000 C.S. 
3. 1 : 100,000 ,, 
4. 1:250,000 „ 
5. 1 : 500,000 „ 
6. 1 :1,000,000 „ 
7. 1 : 2,500,000 C.S. 
8. I : 5,000,000 ,, 
9. I : 10,000,000 ,, 
1. Control—distilled water. 
determine the magnitude of the latter factor the usual method of least 
squares was followed, the individual results being first recalculated by taking 
the mean of the control series as 100. In this way the following table was 
obtained:— 
Concentration. 
Value of Result. 
2. 
1 :50,000 
12-25 + 0.25 
3 - 
1 :100,000 
12-0 +O.25 
4 * 
1 :250,000 
13*5 ±0*5 
5 - 
1 : 500,000 
22-0 +1*5 
6. 
1 :1,000,000 
4 6 '5 ±2-5 
7 - 
1 : 2,500,000 
86-5 + 4*5 
8. 
1 .-5,000,000 
101-0 + 3-0 
9 - 
1 :10,000,000 
94.0 ±2.5 
1. 
Control 
100-0 + 4-5 
