92 Mr. Crum on the Potato Disease. 



17 th December, 1845. — The President in tlie Chair. 



Mr William Ambrose was admitted a member of the Society. The 

 tables of mortality in the metropolis for 1845, were presented by Dr. 

 R. D. Thomson. On the motion of Mr. LiddelL, a sum not exceeding £35, 

 was unanimously voted for the purpose of procuring a President's chair, 

 and a table, for the Hall. 



Mr. Gordon gave an account of Auld's Patent Self-Regulating Damper 

 for Steam-engine Boilers. 



Dr. Findlay stated that in some specimens of diseased potatoes ex- 

 amined by him, the skin of the tuber (both the cutis or external skin, and 

 the cutis vera, or under skin), was quite sound, and the cells quite un- 

 injured for some distance below the skin. 



The disease appeared to be entirely isolated ; the diseased cells being 

 contracted and filled with a brownish fluid. He conjectured that the 

 cells had been previously ruptured, since if they had been entire, the 

 mere change of the fluid, or colour of the fluid contained in them, could 

 Dot possibly have caused them to contract. 



In another specimen, apparently more diseased, in one part there were 

 brownish empty bags, arranged longitudinally, which might be the dis- 

 eased cells deprived of their contents ; on each side there was a canal 

 quite destitute of all solid matter. And, in another portion, considerably 

 more decayed, there were brownish, fibrinous looking, long streaks of 

 solid matter, with perfectly defined edges, which might have been the 

 cells, or the tissue of the cells in a further stage of the disease. The 

 neighbourhood of these last mentioned elongated bodies was quite free 

 from all solid matter, showing, that from whatever source they derived 

 their solidity, it was at the expense of the whole organised structures in 

 their vicinity ; or, at least, that they became solid, and the contiguous 

 structures were destroyed simultaneously. 



7 th January, 1846. — The President in the Chair. 

 Mr. James Thomson was admitted a member. 



XV. — Additional Observations on the Potato Disease — Quantity of Water 

 in Sound and Diseased Potatoes. By Walter Crum, Esq., F.R.S. 



In the month of November, I read to the Philosophical Society an 

 account of some experiments on the potato, from which it appeared that 

 simply by bruising a sound potato, and exposing it to the air, all the 

 appearances are assumed which accompanied the diseased potato of the 

 past year. I mentioned the production in a few days of fungi of various 

 kinds on the surface of the artificially diseased mass, and showed that 



