In this report Professor Humphrey gives an account of some experiments upon potato scab. The following are results of field treatments : "1. Deep planting appears to tend to diminish the development of scab, though further experiments in this direction are very desirable. 2. While the very dark potatoes were wholly free from scab, little or no difference was to be noticed in the susceptibility of the three light varieties planted. . 3. The potatoes raised on barn-yard manure were markedly more scabby and more deeply scabbed than the rest. 4. Tobacco dust in the drill had no appreciable effect in increasing or diminishing the scab. 5. Scabby "seed" produces a crop neither better nor worse than that grown from smooth potatoes." Professor Humphrey distinguishes two forms of scab, the "surface" and the "deep." "It is certain that our disease is the same as that discussed by German writers, and that it is not caused by any parasitic organism. Several years' observations at this station point, also, to the correctness of the view that the cause of our trouble is to be sought in peculiar physical or chemical conditions of the soil, though the opinion that excessive moisture is a sufficient controlling cause seems hardly tenable".