130 



KNOWLEDGE ♦ 



[Aoj. 14, 181 



fissailants, and none have appeared since. It is remark- 

 able tliat although aphides of one species do not 

 seem absolutely confined to one plant, they may swarm 

 fur weeks on the one they like best, and not one 

 will go to another tree or plant almost in contact with it. 

 With regard to their various enemies, thej' unfortunately 

 often fail to appear when they are most needed, and on 

 occasion of a recent search in a kitchen-garden, where 

 many sorts of aphis were enjoying themselves on currant, 

 plum, apple, and other trees, not a single iiseful opponent 

 could be found. It is interesting to pick off from any 

 leaves the cast skins of any of these creatures, and note 

 the extent of the moulting process. The outer layer of 

 the cornea of the compound eyes comes off like a pair of 

 spectacles, and the integument of the antennte, and even 

 that of the fine, piercing bristles is also shed. The 

 piercing bristles deserve minute study. When in use, 

 their action must differ from the whip-like cilia of the 

 monads which are lashed about in the water. The slender 

 piercers of the aphides have to be inserted into tissues of 

 considerable resistance, and it is wonderful how those of 

 the Stoma/pJns qiiercus can be thrust into oak bark. I 



MR. DKXNING REJECTS HIS 

 METEORIC DISCOVERY. 



T.v PvifiiAini A. Proctor. 



M 



R. DEXNI 



n.l 



iHv, 



observatio 



of I 



•ting that tli( 

 I had based ray opinion that sc 

 ejected from giant suns with 

 those formerly recognised, ha^e 

 objection to this withdrawal fi 

 ejection theorj- of meteors reiiuii 

 before Mr. Denu:' 



1. Tupman (on whose au- 

 iil accepted Mr. Denning's 

 meteor-radiants as proved) 



-elocities on which 

 r systems v 



ndbcforr ( 

 But ^Ir. 1)1 





. fo 





do not exist, Mr. Denning !i:!s bei 

 Tupman has been misled. 



There is positively no escape fro 



— The piif a from which 



excluded. 



D and bristles of Stomi 



is quercus. 



have not seen it, but take the figure from Buckton's 

 admirable work. An examination of many aphis' bristles 

 with powers up to an oil immersion 1-12, lead me to 

 think the secret may be in their being hollow, so that 

 Ihcy <:,^Yi;ly, stiffened by the injection of some fluid. It 

 is c\-,Qt, .,f,i~r. those of the oak aphis would be useless as 



More than one species may be in the habit of attacking 

 the same plant. Thus Curtis says, three, if not four 

 assail the turnip. The mischief they do often amounts 

 to an immense sum in pecuuiray value, and Buckton 

 cites an authority to the effect that the "fly," as the 

 u-rowers call it, lessened the hop duty in 1802 to the 

 rxtent of £86,000. 



I remarked before that the sweet honeydew secre- 

 tion does not attract bees who may be feeding close 

 to leaves covered with it. To test this matter 

 still further, I put a bee in a wide tube with 

 ,1 leaf quite sticky with the honeydew, and though 

 the insect was detained for several hours, it never 

 touched this kind of sugar. At this time, however, 

 there are plenty of flowers in bloom. Pettigrew states, 

 in his "Handy Book of Trees," that the bees take it in 

 times of scarcity, and that it spoils the honey. Oaks, 

 .sycamores, limes, and beeches often yield a large supply. 



Papee-Making in Japan. — Scarcely ten years have elapsed since 

 the first paper-mill was started in Japan, with the latest appliances 

 of American and European machinery, and now there are a dozen 

 mills in operation in that country, several of them earning good 

 dividends 



elusion, without rejecting mathematical principles. The 

 matter is not one of theory at all, but of simple geome- 

 trical and kinematical facts. 



Here is the reasoning, every point in which is incon- 

 trovertible, thoiigh it may not necessarily be obvious to 

 persons unacquainted with mathematics : — 



1. Meteor tracks in the sky represent the real tracks 

 of bodies passing through our air. 



2. A set of meteor-tracks radiating apparently from a 

 point are iu reality parallel, unless we suppose such 

 apparent radintinn :i niirr accident (an explanation 



■■''"" imI Col. Tupman). 



1 villains unchanged in position 



liiiur by hour or month by 



our air from outside, — unless 



-ed to be within the earth's 



neither Mr. Denning nor 



3Jected by ^Ir. I 

 i. When sncli 

 among the stars, 

 month, the metec 

 the star-sphere 1 

 atmosphere (which I belie 

 Col. Tupman imagines). 



4. Where the radiant of a meteor-system remains un- 

 changed for hours the velocities of the meteors of that 

 system must greatly exceed the velocity with which, 

 owing to the earth's rotation, the observer is being 

 carried around the earth's axis. 



5. Where the radiant of a meteor-system remains un- 

 changed for months the velocities of the meteors of that 

 system must greatly exceed the velocity with which, 

 owing to the earth's revolution, the observer is being 

 cai-ried around the sun. 



Mr. Denning and Col. Tupman assert confidently that 

 no meteors travel with velocities enormously exceeding 

 the velocitv with which the earth travels roimd the sun. 



