The Woburn Pot- Culture Experiments , 1913. 413 
The wheats ripened off in August, the nitrate sets being 
then very ragged in appearance. Photographs were taken of 
the different sets, and also measurements of the straw and ear. 
As regards these latter, it will be sufficient to say that, in the 
case of the phosphate and carbonate, while the application of 
*01 per cent, of zinc gave about the same length of straw and 
ear as did the untreated sets, a higher amount of the metal in 
all instances reduced these measurements. With zinc nitrate 
there was a still further reduction. 
The crops were cut and threshed out, the roots being also 
at once removed and photographed. 
The comparative results of the weighing of corn and straw 
are given in Table I. In Plate 1 are shown the growing crops 
where an application of *03 per cent, of zinc had been given in 
the different forms, and in Plate 2 are figured the roots corres- 
ponding to the several plants of Plate 1. 
Table I. — Zinc Salts on Wheat , 1913. 
Corn 
No treatment .... 
Zinc phosphate '03 per cent, zinc 
11 
11 
•02 
11 
11 
11 
•01 
11 
Zinc 
nitrate 
•03 
11 
11 
11 
•02 
11 
1 1 
11 
•01 
11 
Zine 
carbonate 
•03 
11 
11 
11 
•02 
11 
11 
11 
•01 
M 
1 1 
11 
n 
” ‘ ‘ ‘ I 
ii 
ii 
ii 
ii 
1 _ 
Grain affected by smut. 
100 
82 
75 1 
99 
34 
68 
127 
79 
83 
99 
Straw 
100 
144 
141 
131 
96 
132 
195 
129 
135 
129 
The duplicates agreed very closely, and the figures given m 
Table I. are calculated on the average of the duplicates. 
It will be seen that in no case did the carbonate or 
phosphate of zinc give an increase of corn above the “ no 
treatment.” There was, however, a general increase m the 
weight of straw. This was the result of the improved tillering 
shown throughout the treated sets. From the phosphate and 
the carbonate there appeared to be no stimulating effect except 
as regards the increased tillering produced. On the other 
hand, a new feature was introduced in the production of 
“ blind ” ears, as if the presence of zinc had affected the plant 
at the time of flowering. x , ,, . , 
With nitrate of zinc, while -03 per cent, of the metal 
produced a marked toxic effect, which was also present to a 
less extent when -02 per cent, was used, with *01 per cent only 
there was a decided stimulation, both corn and straw being 
increased. 
