January, 1902.] 



KNOWLEDGE. 



Founded by RICHARD A. PROCTOR. 

 Vol. XXV.] LONDON: JANUARY, 1902. [No. 195. 



CONTENTS. 



^ PAOK 



Cockchafers. By K. A. Bcilkk, b.a., h.sc. (lUustrateilJ 1 



Animal Perfumes and their Origin. Bv R. Ltdekkek .. 4 

 Spectrum of Lightning. By Edwaed C. Pickeeino. 



flllustratedj C 



Constellation Studies. — XII. The Great Hunter and 



his Dogs. By E. Walteb Maunder, f.r.a.8. flllus- 



trateilj .. ' 7 



The Progressive Spectrum of Nova Persei between 



February 22 and November 28, 1901. By Rov. 



Walter SiDOEEAVE?, S.J., F.R.A.s 



Photographs of the Spectrum of Nova Persei, 1901. 



{Plate.) 

 Letters ; 



Nova Persei. By Henry Ellis 11 



Kain-bow before' Su.NRisE. By E. W. .TonNSON ... 11 



Notices of Books 12 



Books Rbceited 13 



Notes fniustrateilj M 



British Ornithological Notes. Conducted by Habet F. 



WlTHERBT, F.Z.S., M.B.O.U 16 



studies in the British Flora. I. — Plant Colonists. 



By R. Llotd Praegee, b.a. flllustratedj 10 



Collecting and Preparing Foraminifera. By A. Eaeiasd 19 



Microscopy. Condmted by M. I. Cross 21 



Notes on Comets and Meteors. By AV. F. Denning, 



F.E.A.S ... ... ... ... 22 



The Face of the Sky for January. By W. Shaokleton, 



F.E.A.S 22 



Chess Column. By C. D. Locock, b.a 23 



COCKCHAFERS. 



By E. A. BuTi.ER, b.a., b.sc. 

 While the vast majority of British insects avoid 

 obtruding themselves on human observation, and so are 

 never seen except by nature-students who specially 

 search for them, there are a few that comport themselves 

 very differently, and hence are more or less familiar 

 objects even to those who are least conversant with 

 natui-e's mysteries. Such insects are of course common 

 species, but their familiarity is not a necessary consei- 

 quence of their abundance. There are many species 

 equally, if not more, abundant, which yet are absolutely 

 unknown to any but the professed entomologist. These 

 well-known species attain their notorietj' partly, it may 

 be, from their size, but chiefly because they do not shun the 

 busy haunts of men ; and even in their o^^ni native woods 

 and fields, instead of keeping under cover, they are 

 inclined to roam, and so often encounter pedestrians. 

 These remarks apply very forcibly to the subject of the 

 present paper. From early childhood, all counti-y 

 residents must be familiar with cockchafers, and even 

 the townsman may know something of them, provided 

 only that bricks and mortar have not absolutely banished 

 nature's gi-eenery from his neighbourhood. The blind 



and blundering, headlong, whirring flight of the cock- 

 chafer, its proneness to enter at open windows, and cling 

 to bedroom drapery, the pertinacity of grip it manifests 

 when once it has alighted on ciu'tains, dresses, or even 

 it may bo, on ladies' hair — these are all familiar ex- 

 periences in the summer months. The insect, so apt 

 thus to make itself a nuisance to the public generally, 

 as well as a plague to agriculturists, has many interesting 

 features and is well worth a close and detailed study. 



Let us look at it firet in its adult condition. A bulky, 

 and solid-looking creatiu"o, chestnut-coloured above and 

 black beneath, about an inch in length, with a pointed, 

 downward bent tail, six powerful legs ending in strong 

 hooked claws, and a pair of substantial membranous 

 wings stowed away under two homy coverings, the whole 

 insect dusted over with what looks like a mealy powder 

 — such in brief is the Common Cockchafer or May Bug 

 {Melolontha vulgaris) (Fig. 1). From the structure just 



Fjo. 1. — Male Coeki-hafer. 



outlined we gather that the insect belongs to the order 

 Coleoptera, or beetles. The mealy powder with which 

 it is covered pretty easily rubs oflF, so that after knocking 

 about for a while in the world the cockchafer begins to 

 look threadbare and frayed, and shows its chestnut 

 ground colour more distinctly. 



The apparent mealy powder shows under the micro- 

 scope as little white scale-like hairs lying side by side 

 and pointing backwards. They are more thickly strewn 

 in some parts than in others, and the females have a 

 particularly dense covering of them. On the breast they 

 are replaced by a shaggy covering of long yellowish 

 hairs. All along each side of the abdomen, just below 

 the edges of the wing-covers, is a row of snow-white 

 triangular patches made of similar and still bi'oader 

 scales, each patch being sharply outlined and bounded 

 by the general black surface — a striking colour scheme 

 which vastly improves the appearance of the insect and 

 redeems it from absolute plainness. This covering of 

 scales and haii-s makes the cockchafer an instructive 

 insect for illustrating the gradual change of an organ 

 of given elemental shape into one altogether difl'erent. 

 A careful examination under the microscope will show 

 that even the broadest of the scales are merely expanded 

 hairs, and from different parts of the body a selection 

 might easily be made of all varieties of these appendages 

 ranging from the naiTOwest (Fig. 2), which would un- 

 hesitatingly be called hairs, through a series of minute 

 modifications whose exact name would be doubtful, to 

 what again would be unliesitatingly described as scales. 



The last segment of the abdomen tapers away to a 

 point which is differently shaped in the two sexes, that 

 of the female being much the blunter of the two. This 

 pointed tail proved in fonner days an in-esistible 

 temptation to the mischievous youth of England, who 



