1. Internal Disease has been found to occur throughout numerous samples of potato of known variety such as for example: “The Sutton Flourball,” “Sharpe's Express,” etc.; similarly, Streak-disease has been found in samples of certain other varieties such as: “British Queen,” “Edina,” “Duke of York,” etc.

2. Well-developed Internal Disease has been detected in very young tubers.

3. The markings in Internal Disease and Streak-disease may or may not form a connected system in the tissue of the potato, sometimes the discoloured areas are quite isolated. The diseased cells can be easily traced to within a few cells of the cork-layer (skin). In Streak-disease they can be occasionally traced right up to the cork or to a slight injury to the surface of the tuber.

4. No trace of a hyphal organism could be found either within the cells or intercellular spaces of diseased tissue. The cells are killed, often retaining their starch in an unaltered condition. If the disease is propagated from cell to cell it takes place without an easily visible deterioration of the cell-wall in the initial stages.

5. Internal Disease and Streak-disease did not spread in store under the experimental condition described.

6. In every experiment samples of potatoes affected with Internal Disease and Streak-disease whether planted in Devonshire or Northumberland produced a certain proportion of tubers affected with these diseases.

7. The diseases in question are frequently complicated by the presence of Phytopthora infestans in the field and Fusarium solani in the pit or store.