816 



the cause of the disease to have been satisfactorily ascertained, when 

 scientific men actually knew nothing whatever about it, in his opi- 

 nion, was calculated to produce very considerable mischief. He 

 even saw it stated in a leading article in the ' Times ' a few days ago, 

 as a settled fact, that the potato disease was caused by the Aphis 

 vastator, and yet he had been unable to find a single scientific man, 

 capable of trustworthy investigation, who gave the slightest counte- 

 nance to such an absurdity. The chairman, in conclusion, mentioned 

 tha names of several of the leading botanists and naturalists of 

 France, Belgium, America, and England, who were all opposed to 

 Mr. Smee's theory. 



Dr. Ayres said, in allusion to Dr. Parkin's publication, that he 

 did not think the action of muriate of soda upon carbonate of lime 

 would extricate carbonic acid, unless additional acid already existed 

 in the soil. In reply to a question from the chairman, he added that 

 he had examined a quantity of diseased leaves of the potato plant 

 without being able to find even the skin of an Aphis upon them, 

 though it was well known that these animals frequently changed their 

 coverings during the season. 



Mr. Hassall said he perfectly agreed with what had fallen from 

 the chairman respecting the Aphis. In his opinion the potato-dis- 

 ease was caused by Fungi, and this view was strengthened by the fact, 

 that if the sporules of a fungus be shaken over a sound tuber, or 

 other soft cellular tissue, the disease will be produced in a few hours. 



Mr. N. B. Ward said he visited Ireland in July last, and traversed 

 an extensive district in company with one of the most distinguished 

 of living botanists — Dr. Harvey, of the University of Dublin — but 

 though they saw field after field destroyed by the disease in a single 

 night, they could only arrive at the conclusion that neither Fungi nor 

 Aphides had anything to do with producing the disease. That they 

 were, in fact, the result, and not the cause, and that the origin must 

 be traced in some atmospheric influence. 



Mr. Hassall would not deny that the atmosphere had a powerful 

 existing influence in extending the disease, but he did not think it 

 was the proximate cause. He did not consider it scientific to follow 

 the old system of attributing all diseases of which the origin was 

 doubtful to the influence of the atmosphere. 



Mr. Ward said, in attributing the disease to atmospheric influence, 

 he merely intended to intimate that he had no knowledge whatever of 

 the real cause of the disease. 



The Chairman said, Fungi and insects made their appearance in 



