Januaky, 190H.] 



KNOWLEDGE 



Founded by RICHARD A. PROCTOR. 



Vol. XXVI.] LONDON: JANUARY, 1903. [No. 207. 



CONTENTS. 



Animal Wind-Bags^Useful and Ornamental. Wind- 

 Bags and Love-Displays. By W. P. Ptcraft, a r. s., 

 I'.z.s., etc. {Illustrated) ... ... ... ... ... 1 



Whorls and Crests of Hair as Animal Pedometers. 



By Waltkb Kidd, m.d., f.z.s. {Illustrated) ... ... 3 



The Sun's Dusky Veil. By Miss Agnes M. Clebke ... 7 



Photographs of Comet b 1902 (Perrine). By Isaac 



RoBKiiTS, 11..S0., r.K.s. {Plate) ... 9 



The Lunar Eclipse of 1902, October 16 9 



Letters : 



Ti[R VisiBitiTT OP THK Crescent op Venus. By T. H. 



AsTBURY ... ... ... ... ... ... ... 10 



Habits op Sanitation. By M. S. S. ... ... ... lo 



Notes 10 



British Ornithological Notes. Conducted by Harkt F. 



WiTHBRBT, P.Z.8., M.B.O.ir 12 



Notices of Books 12 



Books Eeceifed 13 



The Nobodies, — A Sea-faring Family.— V. By Rev. 



T. R. E,. Stebbino, M.A.,p.R.s.,v.p.L.s., F.z s. {Illiistrateil) 1-t 

 Familiar British Wild Flowers and their Allies. I 



The Pea Family. By R. Lloti> Pbaeoer, d.v. 



(Illustrated) ... ... ... . . . 17 



Microscopy. Conducted by M. I. Cross. {Illustrated) ... 20 

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



P.R.A.S ... .' 22 



The Face of the Sky for January. By W. 



Shackleton, f.e.a.S. {Illustrated) 22 



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



ANIMAL WIND-BAGS-USEFUL AND 

 ORNAMENTAL. 



WIND-BAGS AND LOVE-DISPLAYS. 

 By W. P. Pyceapt, a L.s., f.z.s., etc 

 It is astonisliing, wheu one comes to reflect ou the matter, 

 how many nnd quite unrelated animals have adopted the 

 same tactics, thonijh bv very different means, to gain some 

 particular end. whereby they may obtain some advantage 

 over their neighbours in the "struggle for exisienc"e. 

 VViud-bags or " air-sacs " of some sort or another seem to 

 have been especially favoured. By their means the form 

 of the body may be temporarily cliangcd, thereby 

 rendering the animal unlike its near allies, but superficially 

 like that of some other creature or even inanimate object, 

 or they may serve as voice organs, whereby their possessors 

 may charm their mates, or strike terror" into the heart of 

 an enemy. Yet again, they may serve the purpose of a 

 substiintiul banking account, and enable life to be got 

 tlirough with the least possible expenditure of energy. " 



These wind-bags, which, almost without exception, may 

 be inflated and deflated at the will of the animal, differ 

 much in the nature of their origin. In many cases they 

 are formed by more or less extensively enlarging parts of 

 the gullet or of the windpipe, without disturbing their 

 normal functions. In others the air is drawn into special 

 receptacles Wind-bags of the latter type, however, have 

 also been developed as auxiliary breathing organs, as in 

 the ease of birds, for instance. With these we have no 

 concern here ; their description awaits special treatment. 

 In the present series of articles, of which this is the first, 

 we propose to deal only with those air-sacs which are 

 concerned with purely external phenomena. 



The development of purely ornamental wind-bags, used 

 as adjuncts in courtship, forms the theme of the present 

 chapter. The most conspjicuous and successful patrons 

 of this form of display are to be found amongst the ranks 

 of the highly excitable, and always beautiful birds. 



Thomson's assurance that " the lover is the very fool of 

 Nature " seems particularly applicable to displays of this 

 kind. Take the common pigeon for example. Could any- 

 thing appear more silly than the strutting, bowing and 

 cooing of the cock aided by this very practice of filling his 

 gullet with intoxicating draughts of the morning air, the 

 which swells his neck to unduly large proportions, and 

 apparently, on this account, make him so much the more 

 fascinating ? But the past-master in the art of windy 

 love-making among the pigeons is the domesticated 

 variety known as the pouter. 



As with the pigeon tribe, no special receptacle is pro- 

 vided for the indrawn air, but that portion of the gullet 

 known as the crop has been enormously enlarged so that, 

 when fully inflated, it exceeds the body itseK in size. The 

 present greatness of this crop, we would point out, is due 

 not so much to the efforts of the prancing bird as to the care 

 and selection of the breeder. For this display, strangely 

 enough, has found favour even among men ; consequently, 

 the very finest performers only are selected to be the 

 parents of the next generation, and these parents are 

 themselves, of course, descendants of equally distinguished 

 birds. The part the breeder has played has beeu to select 

 carefully from his young birds those which prove the best 

 performers. From these he raises new stock. Their un- 

 skilh'd kindred go to make pigeon pie, or meet some other 

 ignoble fate. 



A stiU more remarkable gullet pouch is that of the 

 frigate-bird of the Tropics ; a near ally of the cormorants 

 and gannets. Bare externally, of a vivid scaidet colour, 

 and capable of being inflated till it is nearly as large as 

 the rest of the body, this pouch is an invaluable asset to 

 its possessor wheu seeking a mate. For here, as else- 

 where, the successful suitor is he who makes the most of 

 his peculiar charms; the jirize falling to him who is able 

 to display the biggest and most brilliantly coloured pouch. 

 Only the males wear this ornament, which is retained only 

 "luring the breeding season. At this time a lively com- 

 petition appears to take jilace, a dozen or so of these birds 

 crowding together in a tree and greeting the apjtroacb of 

 their }>rospective mates with inflated pouches and drooping 

 wings, accompanied by a peculiar apology for a song, 

 described as a sort of "' wow-wow-wow-wow," and a noise 

 resembling the sound of castanets, which is made by a 

 violent chattering of the horny beak. 



The pouch of the frigate-bird is formed by the upper 

 end of the gullet, aud appears to bo closed behind by a 

 peculiar arrangement of muscular fibres to form what is 

 known as a sphincter muscle. These muscles close up the 

 tube of the windpipe mucii as the mouth of a bag is closed 

 by means of a double string. 



The American prairie-hen. or pinnated grous(<. has long 



