In three years of experiments at Iowa Agricultural Experiment Station in the use of formaldehyde gas for treating seed potatoes for scab, it was found that the gas greatly reduces the germinating powers of the tubers. The injury not only affects the eyes, preventing germination, hut also causes sunken spots about the lenticels. The tubers absorb the gas and retain it and thus are poisoned. In experiments with the usual treatment for potato scab, where the seed is soaked in‘ standard solutions of formaldehyde or corrosive sublimate, it was found that injury results if the tubers are soaked for more than two hours, the injury increasing with the length of treatment. It was also found that in soaking tubers in standard solutions for potato scab they should be placed in the solution whole and not be cut for planting before treatment. Cut tubers when treated for only two hours showed a marked decrease in germination
