The object of the experiments described below was to establish, more clearly to what the fungicidal value of alkaline sulphide solutions is to be attributed.

INTRODUCTORYIN a previous communication 1 we have adduced evidence to show that solutions of alkaline sulphides are probably of fungicidal value owing to the polysulphides which they contain.This work has been continued along similar lines, and the following account gives the main results obtained during the past three years 1916-18. During the first two years a number of ammonium polysulphide solutions were made according to different methods, and the fungicidal value of each determined with a view of ascertaining whether a relationship existed between the polysulphide sulphur content and the fungicidal action of these solutions.During this period evidence accumulated that the death-point of the mildew (Sphaerotheca Humuli (DC.) Burr.) varied according to its stage of development.In 1918 by the selection of suitable material a method was adopted whereby any two solutions could be very strictly compared with regard to their fungicidal action. Thus it could be determined whether the nature of the polysulphide was of importance. METHODS.While the general methods used in our experiments in 1915, which have been described in detail 2 , were adopted in our work in 1916-18, it was found necessary to pay closer attention to the stage of development of the mildew-patch sprayed. On this point we wrote in 1915: 'The plant used for spraying was carefully selected as bearing on a number of its leaves young and vigorously-growing patches of the mildew in its conidial stage. In order to make the experiments as strictly comparable as possible only those patches of mildew were used where the 1