176 
J. J. SKINNER AND F. R. REID 
each are given in the two charts of figure 7. In table 5 are given the average 
weights of the cultures arranged according to their P2O5 content. It will 
be observed that this neutral phosphate salt had a similar action in amelior- 
ating the effects of the crotonic acid to that of the two acid phosphate salts 
used in the former experiments. 
Table 5 
Showing the influence of phosphate in overcoming the harmful effects of a-crotonic acid. 
Green weights of wheat plants in nutrient solutions composed of Na2HP04, 
NaNOs, and K2SO4. Cultures arranged according to content of P2O5. 
Parts per Million of 
Average Green Weight of Culture 
Percentage Decrease 
Culture No. 
P2O5 in Nutrient 
Without Crotonic 
With 25 P. p.m. 
or Increase in Cro- 
(See Fig. 2) 
Solution 
tonic Acid Culture 
Acid 
Crotonic Acid 
grams 
grams 
I 
80 
1.62 
1-57 
- 4 
2- 3 
72 
2.06 
2.05 
0 
4- 6 
64 
2.66 
2.57 
- 3 
7-10 
56 
2.82 
2.58 
- 8 
11-15 
48 
3-13 
2.84 
— 10 
16-21 
40 
2.89 
2.98 
+ 3 
22-28 
32 
2.79 
3-07 
+ 10 
29-36 
24 
3-24 
2.87 
— 12 
37-45 
16 
3-31 
2.86 
-14 
46-55 
8 
3.28 
2.27 
-30 
56-66 
0 
3.06 
1.58 
-49 
In the group of cultures containing no phosphate there was a reduction 
of 49 percent in growth due to the compound while there was scarcely any 
reduction in the cultures containing a large percentage of this element. 
This point is again brought out when the cultures of the two triangles 
are arranged in groups, composed of the mainly phosphatic solutions, sub- 
FiG. 8. Showing the effect of di-basic sodium phosphate in overcoming the harmfulness 
of cc-crotonic acid. Bottles marked A contain 25 p. p.m. a-crotonic acid. 
Nos. I and lA contain no P2O5, 40 p. p.m. NH3, and 40 p.p.m. K2O; 
Nos. 2 and 2A, 8 p.p.m. P2O5, 40 p.p.m. NH3, and 32 p.p.m. K2O; 
Nos. 3 and 3A, 24 p.p.m. P2O5, 32 p.p.m. NH3, and 24 p.p.m. K2O; 
Nos. 4 and 4A, 40 p.p.m. P2O6, 24 p.p.m. NH3, and 16 p.p.m. K2O; 
Nos. 5 and 5A, 56 p.p.m, P2O5, 16 p.p.m. NH3, and 8 p.p.m. K2O; 
Nos. 6 and 6A, 72 p.p.m. P2O5, 8 p.p.m. NH3, and no K2O; 
