No. XV.B.] APPENDIX. 227 



ducts. In the former part of this subject Mr. Smee, who has given it great 

 attention, has procured specimens of diseased bulbs in almost every stage 

 of the blight : from these he has obtained sections passing through the 

 sea.t or origin of the disease, and, by a proper arrangement of the sections, 

 he has succeeded in exhibiting its progress at one comprehensive glance. 

 He has also obtained several specimens of the Aphis vastator, or destruc- 

 tive insect, to the agency of which the ruin of the potato, and indeed of 

 other plants, has been attributed. Mr. Smee placed them under the 

 lenses of powerful microscopes, twelve of which were adjusted at one table. 

 Amongst the specimens of potatoes sent up were some from the estate of 

 the Bight Hon. the Speaker of the House of Commons, in Hampshire. 

 They were also accompanied by some large plants, and by leaves of the 

 mangold-wurzel destroyed by the Aphis vastator, which in some instances 

 was found upon the plant itself. Other diseased specimens of the forth- 

 coming crop have been received by Mr. Smee from various other parts of 

 the country. Amongst the substitution for potatoes and bread Mr. Smee 

 exhibited fourteen loaves made from as many different materials. Amongst 

 them might be mentioned those of hay, sweet beet-root, turnips, carrots, 

 parsnips, mangold-wurzel, Iceland moss, and hay biscuits. Many of these 

 are unquestionably very palatable and nutritious, as, for instance, the 

 bread from turnips, carrots, and beet-root. The hay biscuits and bread 

 are most singular compounds. They are of a deep brown colour approach- 

 ing almost to black, possess all the fragrance of hay, and are nutritious in 

 a high degree. Of their nutritious powers, indeed, there seems to be no 

 question; the grand point to be ascertained is their susceptibility of 

 yielding to the action of the digestive organs. Most of the other breads 

 mentioned above are of the same colours as wheaten and maize." 



No. XV.B. 



ON THE POTATO DISEASE, 1845-46-47. 

 By ALFRED SMEE, F.R.S. 



THE APHIDES AND THE APHIS VASTATOR. 



As reported by ED. LATHAM, Royal General Dispensary, Aldersgate Street. 

 ON Wednesday evening, March 10th, 1847, A. Smee, Esq., F.R.S., Surgeon 

 to the Bank of England, &c., delivered at the London Institution a 

 lecture on aphides and on the Aphis vastator as being the cause of the 

 potato disease, &c. The following is the substance of Mr. Smee's 

 lecture : 



I feel deep responsibility in coming before the public to consider the 

 subject of the present scarcity of food. My observation has proved to me 

 that the cause of this scarcity is a plague of insects, resulting from a pre- 

 ternatural abundance of those insects, and their settling, feeding on, and 

 destroying various kinds of plants. History records numerous devas- 

 tating plagues of insects analogous to the present ; immense and almost 

 incredible swarms of locusts, which destroyed every green thing, are 



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