It is to be noted, fortunately, that the defect is comparatively rare, and seldom appears on estates which employ an anti-coagulant in the field. While we have examined persistent cases, one of which led to a temporary discontinuance of the preparation of smoked sheet rubber, we have not yet been able to arrive at any satisfactory idea of the exact conditions governing the incidence of "blisters." Our investigations only lead us to two observations: (_a_) That blisters have appeared on the rubber of some estates after wintering, and during the period of new leaf-development. (_b_) That the defect has been noted on other estates during a period when there were frequent but not heavy rains, and when there was a comparatively low average temperature. In either case, as the factors are beyond human control, it would be expected that without any change being made in estate procedure, the trouble would vanish as mysteriously as it appeared. This is our experience; but as showing the possible intensive effect of a high temperature in the smoke-house, it may be remarked that very infrequently, in a batch of sheets exhibiting ordinary bubbles, a few hanging directly above the furnaces show signs of a slight blistering effect. "SPOT" DISEASE IN SHEET RUBBER.--That "spot" disease may appear in air-dried sheets was evident at the beginning of the outbreak in the spring of 1911. The first cases noticed took the form of pink and bluish "blushes" spreading over the whole of the sheets. Later, fungoid spots began to appear. These mainly took the form of red or black blotches, and were very unsightly. As "spot" disease cannot develop in smoked rubber, the obvious and simple course to adopt was to smoke-cure the sheets. When it is stated that "spots" do not develop in smoke-cured rubber, it is understood that the smoke-curing must be efficient and must commence as soon as the rubber has been rolled, and the surface water has drained away. If the sheets are allowed to air-dry for a few days, the disease may develop, and then smoke-curing will not get rid of the coloured patches. The operation of smoke-curing will not get rid of the coloured patches. The operation of smoke-curing may tone down the colour, but the spots would still remain evident.