A practical adaptation of a method devised by Miss Glynne for testing indoors the immunity or susceptibility of potato varieties to wart disease is described. The method consists of infecting by summer sporangia the young sprouts of the tubers under test. Extensive test has given such satisfactory results that there is little doubt that the method is infallible.

The writer wishes to render his grateful thanks to Mrs N. McDermott, who has been actively associated with him throughout the work described and who is largely responsible for the technique employed; to Miss M. D. Glynne, of the Rothamsted Experimental Station, for her many helpful suggestions; to Mr W. H. Parker, Director of the National Institute of Agricultural Botany, Cambridge, for his assistance and advice; t o Dr R. N. Salaman for supplying material for test, and to Dr G. H. Pethybridge for his kindness in examining tubers sent to him.