ADDITIONAL NOTES. 



by the aphis ; as leaves of the nut-trees in my garden on the 



of the Derwent are every year crowded with innumerable aphifes 



I 



on their inferior furfaces, and yet I have fecn few, if any of them, on 

 nut-trees in fome higher fituations, which I happened to infpe6t. Add 

 to this, that the great .honey-dew, mentioned in SeO:. XIV. i. y, 

 was produced on a row of willows by the fide of water. 



This 



may 



neverthelefs be in part afcribed to fome other local circumftance ; as 



X 



I this year obferved numerous large black aphides round the ftalks of 

 garden-beans on a clayey foil, which did not exift in my garden, 

 which may be called a carbonic foil. Though on the peach and nec- 

 tarine trees, againil: the walls in my low garden, and on fome plum- 

 trees, the aphides .exifl almofl: every year in fuch deflructive mul- 



r 



titudes as to prevent the fruit from fucceeding, and thence to rend 

 them not worth cultivation ; and to render the leaves of the nut 



r 



trees lefs in fize, and lefs prolific than other nut-trees on a more c 

 vated and clayey foil, with which I this year compared them. 



Why the aphis fhould be fo much more numerous in moid fit 

 tions is a curious fubje^t of inquiry, but is fo fimilar to another a 

 mal fad, .that they may iliuftrate each other. The cough and o 

 fequent confumption of Iheep, which occurs annually in moill fit 



tions^ is owing to an infe61; called a fleuk-worm, about the fize and 

 ihape of a child's finger-nail, which creeps up the gall-duds from the 



les, and preys upon the livers of fheep ; as may be feen in 



fti 



moift feafons 



fhambles. This feems 



occur ft 



the b 



becoming too dilute from fo much watery nourifhment in thofe 



I 



mals, and that thence it d 



polTefs fufficient bitternefs 



acri- 



mony to prevent the depredation of thcfe infeds, as in drier feafons. 

 Ob the fame account I fufped the juices of nut-trees and of willows 

 planted in very moid fituations may be rendered too dilute ; but that 

 higher fituations they may poflefs fufficient acrimony or bitternefs 



mixed with the fap-j 



See Sea. XIV. 2. 8 



P 



th 



depred 



of th 



e 



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6,Tc 



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