FOREIGN NOTICES. 



427 



they cannot agree whether those "insects" are 

 mites, worms! or scrubs, flies, perfect or imperfect, 

 Thrips or Eupteryx or Aphis. 



We have read Mr. Smee"s book with care; we 

 have endeavored to make out his argument, and to 

 do justice to his evidence, and we can only express 

 our wonder that he shouhl not have perceived how 

 inconsistent even with his own knowledg'e of facts 

 is this insect theorj'. For what are the grounds 

 on wliich he has founded his opinion? Firstly, 

 that the aphis is found on the potato plant; 2dly, 

 that it multiplies very fast; 3dly, that it punctures 

 the leaves; 4thly, that it fills the air with its my- 

 riads, and is found even in the streets of London ; 

 5thly, that where the insect has damaged the leaf 

 of a plant, it (the leaf) is much influenced by wet 

 weather; 6thl}^, that the first appearance of the 

 disease in a healthy and previously undamaged 

 plant is alwaj'S subsequent to the visit of the de- 

 stroyer; and the amount of disease, cceteris pari- 

 bus, is directly proportionate to the number of 

 insects wliich take away the vital fluid of the 

 plant." 



We may very well concede the three first pro- 

 positions; they are vvell known to be true. The 

 fourth is a mere local fact; for we cannot suppose 

 Mr. Smee to assert that myriads of Aphides are 

 found over every potato field; if it were so, we 

 and others must have been very unfortunate not to 

 perceive them. The fifth is a strong assertion, in 

 support of which we cannot discover a trace of 

 evidence; and it might be disposed of by a counter 

 assertion, that " when the leaf of a plant is injured 

 by aphides, the leaf is less influenced than before 

 by wet weather." We do not, however, deny 

 that the punctures of aphides may be in some de- 

 gree affected by wet weather; but how? — by a ge- 

 neral destruction of vitality? — by broad blotches 

 on the foliage ? — by inducing moist gangrene in 

 the whole system? — who ever heard of such a 

 thing! Aphides cause swellings and a thickening 

 of tissue, as may be seen in the Potato as well as 

 other plants; and when they do exist in the myri- 

 ads which are talked of, trees will sometimes cast 

 their leaves, because the stem which bears them is 

 exhausted by the aphides of the organizable matter 

 which feeds the leaves ; hut such cases have no con- 

 cern with the "potato disease." The sixth pro- 

 position is certainly not admissible; it is directly 

 in the teeth of facts which we are all familiar 

 with. Our own potatoes were as much diseased 

 as any crops near London; yet we saw no aphides 

 prior to the appearance of the injury, except a 

 straggler here and there, such as could have been 

 found any year within our recollection. 



Does this aphis notion explain how potatoes, 

 sprouted in sand, in 1845, and which never got 

 above ground, became diseased? How potato- 

 fields screened by trees or strips of other crops, 

 were saved as far as the influence of the screen 

 extended, while all around them perished? How 

 all the Isle of Calf potatoes escaped in 1845, ex- 

 cept the patches belonging to the lighthouse keep- 

 ers? and finally, how in certain countries the dis- 

 ease was unknown except in localities planted 

 with foreign potatoes? What could have kept 



these winged creatures from flying to the neigh- 

 boring fields and biting them? 



We must not, however, part with this book 

 without an example or two of the author's mode 

 of reasoning. He says — 



" When the insect has damaged the leaf of the 

 plant, it is much influenced by wet weather: a 

 shower of rain will fill the stems with water; and 

 in consequence of the solid portion having been ta- 

 ken away by the insect, the moisture cannot cause 

 the rapid growth of the plant which should take 

 place under such circumstances." 



We were not previously aware that aphides fed 

 on solid matter; we had always understood that 

 their food was the Jluid ma.tter of plants. Again — • 



" This vastator does not commit the same 

 amount of mischief upon every kind of potato. It 

 dislikes those leaves where moisture is to be found 

 on the under surface in the morning; and thus, ac- 

 cording to the state of the plant, it passes over 

 with greater or less rapidity." 



Here is certainly a very remarkable discovery. 

 It appears that there are some kinds of potatoes 

 which deposit water on the under side of their 

 leaves during the night, and other kinds that have 

 no such power! Perhaps Mr. Smee can find some 

 kinds of men who perspire by their skin, and 

 others who do not. Until this is shown we must 

 be permitted to adhere to the vulgar opinion 

 that the vital actions of all kinds of potatoes are 

 essentially the same. 



But we would rather not go on. Let us rather 

 advise all who are ambitious of figuring in the pota- 

 to discussion to qualify themselves, in the first in- 

 stance, by an attentive study of the writings of 

 such men as Decaisne, Harting, and Payen, in ad- 

 dition to the well-ascertained facts that may be 

 gathereil from the published documents of this 

 country. — Lindley. Gard. Chron. 



The LiNxiEAN Gold Medal. — To the President 

 and Council of the Linngean Societ}^, London, 

 there is left, under the will of the late Mr. Ed- 

 ward Rudge, of Abbey Manor-house, Evesham, 

 Worcester, a magistrate and justice of the peace 

 for that county and Middlesex, a bequest of X200, 

 the annual interest to be laid out in the purchase 

 of gold medals, to be called the "Linncean Me- 

 dals," and to be awarded by the president and 

 council to the Fellow of the Society who shall 

 write the best communication in each volume, and 

 which shall be published by the Society, in either 

 of the four departments of natural history. Each 

 gold medal to contain on one side a profile bust of 

 Linnffius in his full dress, cncircleil by his name 

 and the dates of his birth and death. On the ob- 

 verse is to be engraved the name of the Fellow of 

 the Society to wh"m such medal is awarileti, en- 

 circled by a wreath of the Linnesan Borealis. — 

 English Paper. 



L^Echo du monde savant, contains a notice of a 

 Manuel Ires intcressant, by M. Louis Dupont, in 

 which it slates the author demonstrates, logically 

 and philosophically, the possibility: 1st, of caus- 

 ing long continued rain storms to cease: 2d. of 



