Additional Notes on the Potato Blight 225 



line of junction in the usual way there may sometimes be 

 found proof that before falling the fungus had infected the foot- 

 stalk, some little black points being discoverable in the upper 

 extremity of the latter. The condition may spread later on 

 through the whole length of the footstalk. As a rule, how- 

 ever, as already stated, if the line of junction be invaded, the 

 flower will not fall. 



What has been said above as to the improbability that 

 former observers have wholly overlooked the flowers applies 

 with equal force to the " sets." Yet I cannot find evidence 

 that any one has thought it worth while to inspect them, or if 

 that has been done to record the results. Of the "sets," which 

 I have sought for during the last fortnight (August 10 to 

 24), in a very considerable number of instances, no trace 

 could be detected. In two or three we found a quite empty 

 and dry rind keeping its form without any trace of decay. 

 In these the growing plant had apparently used up the whole 

 of the parental substance. In others the set, although its 

 shape and size remained recognisable, was so rotten that no 

 special structures could be recognised. In yet others, portions 

 of the outer part remained firm, succulent and evidently 

 living, and in a few of these evidences of disease (brown 

 specks and bands) were obvious. In others the whole set 

 (an uncut potato) in its original form remained little, if at all, 

 altered. On slicing these, traces of disease quite unmistak- 

 able were always found. I examined more than fifteen such 

 still living sets, and found disease in all. They were not 

 rotten but evidently living, as was proved by their being in 

 the act of producing new sprouts. 



It would be premature to base any conclusions on the 

 observations here recorded. They must wait for confirmation 

 or refutation by more extended experience. As they stand, 

 however, they appear to suggest that the symbiotic presence 

 of mycelium in a " set " exercises in some cases a sort of 

 protective influence, preventing on the one hand the absorp- 

 tion of the substance of the set by the new plant, and also the 



