408 
Proceedings of Royal Society of Edinhurgh. [june 18, 
Distilled water, 
Potassimn nitrate, 
Sodium cliloride, . 
Calcium sulphate, . 
Magnesium sulphate, 
Calcium phosphate (Ca3P20g), 
Ferrous sulphate, . 
1 litre. 
1 gramme. 
0-5 „ 
0-5 
0-5 
0-5 
0-08 
The solution was prepared from pure salts, and then sterilised by 
boiling, and allowed to cool in contact with filtered air {i.e., the 
air had to pass through a sterilised cotton-plug), — the object being 
to prevent any fungal spores (that might be present in the 
atmosphere) from falling into the solution. The seedlings were 
now taken up from the soil, washed all over several times in the 
antiseptic fluid, and then placed in slit cork, so that the roots may 
be submerged in the culture fluid and the shoots grow in the air. 
The corks were floated in beakers (fig. 7), placed under bell-glasses, 
and exposed to light and warmth. 
The seedlings were afterwards inoculated by placing pieces of the 
cut fungoid nodules (from the cucumber roots supplied to me by 
Mr Crocker) upon the scratched root-stocks, and then replacing 
them in the culture solutions. From these experiments the following 
results were obtained: — 
Plant 
Xumber. 
Date of Sowing 
Seeds. 
Date of transfer 
to Culture 
Solution. 
Date of Inocu- 
lation. 
Date of Nodules 
first seen on 
Foots. 
1 
September 5 
9 ? 9 ’ 
October 8 
October 9 
November 17 
2 
„ 7 
9 9 9 9 
„ 26 
3 
„ 7 
„ 26 
4 
9 ? 5 9 
„ 7 
9 9 9 9 
„ 26 
5 
9 9 9 9 
,, 6 
„ 24 
6 
9 9 9 9 
„ 6 
5 9 9 9 
„ 24 
A similar number of seedlings grew in a culture solution of the 
same composition, except Od per cent, of ferrous sulphate was 
added as an additional ingredient. The seedlings were inoculated 
after the method just described. No disease structures developed 
in the least — the little plants remaining in the culture solutions 
from October 7th to December 10th. This shows the complete 
destruction of the fungal disease by means of ferrous sulphate. 
When the disease has taken fairly hold of the plants, the fungus 
