iv.] NEW DISEASE OF POTATOES. 23 



who, it may be said, had not seen our note in Nature 

 sent us a box enclosing numerous living examples of the 

 desired black Sclerotia from potatoes grown near Aberdeen. 

 Mr. Wilson informed us in an accompanying letter that 

 he had hundreds of similar examples from the previous 

 year's potato stalks then germinating, and that, judging 

 from the appearance they presented at that time, they 

 would probably produce a Peziza allied to Peziza tuberosa, 

 Bull. At the same time a third letter appeared in Nature, 

 this time from Professor Blytt, stating that he had for- 

 warded examples of the Sclerotia to Professor De Bary, 

 and that they had germinated with him. Professor Blytt 

 stated that the Sclerotiutn had produced a fungus identified 

 by Professor De Bary as Peziza sclerotiorum, Lib., a species 

 which had not at that time been recorded as British. At 

 the period when this discussion was going on we received 

 other living examples of Sclerotia from Mr. Thomas 

 Carroll of the Gilbert Institution, Glasnevin, Dublin. 

 Mr. Carroll stated that the disease was prevalent on the 

 west coast of Ireland, especially on land too heavily 

 manured. On making further enquiries we learned that 

 the disease was spread generally over the counties of 

 Sligo, Mayo, and Galloway, and that it was by no means 

 confined to any special variety of potato ; that the 

 manuring with seaweed had nothing to do with the 

 disease, but that large patches of potato plants twelve to 

 fifteen yards in diameter were destroyed by the spawn of 

 the Sclerotium, and the most luxuriant crops were appar- 

 ently the most affected. The apparent luxuriance of the 

 affected crops was perhaps not real, for it is well known 

 that when some plants are first attacked by fungoid 

 diseases they put on a spurious appearance of luxuriance, 

 and are exqited into a sudden quick growth. It has often 

 been remarked that the apparently most healthy potato 

 plants fall first before the disease caused by Peronospora 

 infestans, Mont. The reason is found in the fact of the 

 spawn of the Peronospora being capable of exciting a sudden 



