482 



KNOWLEDGE. 



December, 1911. 



OUEKETT MICROSCOPICAL CLUB.— October 24th.— 

 Professsor E. .\. Minchin. M.A.. F'.R.S.. President, in the 

 chair. .\n old microscope, sent by Mr. Hugh Paterson. of 

 Sydney. N.S.W.. was exhibited. It had been presented, 

 abont 1850. to his father, by J. T. QneUett. F.K.S. (1,S15-61I. 

 the distinguished niicroscopist. after whom the club is named. 



E. M. Nelson, F.R.M.S. — " .An improved compound iiiicro- 

 scope. by James Mann, 1751,'' was read by the Hon. Sec. 

 The instrument is. in the main, obviously a copy of J. Cuffs 

 (17441. the improvements consisting in the mirror and its 

 attachment, and in making the instrument portable. The 

 first portable compound microscope was made by George 

 Adams, in 1746. and the one now described showed Mann's 

 device for adapting .Adams's idea of portability to Cuff's 

 microscope. Very probably this was the second portable 

 microscope. 



J. W. Shoebotham, N.D.,A. — " .'A general account of the 

 Spring-tails iCollembola)." They were described as belonging, 

 with the orders Protura and Thysanura, to the sub-class 

 Apterygota. of the class Insecta. The anatomy of the Col- 

 lembola was described fully, accounts being given of the eyes, 

 post-antennal organ, pseudocelli, antennal organs, body, legs, 

 and those very typical and curious organs, the ventral tube 

 and the spring. .A tracheal system is usually absent and in 

 the few species possessing one it is very poorly developed. 

 Although they have generally been regarded merely as 

 scavengers, there is now evidence to show that they may 

 do considerable damage to growing crops. Between four 

 hundred and iive hundred species are at present known, of 

 which one-hundred-and-seven have been recorded from 

 Britain. 



Messrs. Watson & Sons exhibited under microscopes an 

 interesting series of preparations of embryos of Decapods. 



THE ROYAL MICROSCOPICAL SOCIETY.— October 

 ISth.— H. G. Plimmer, F.R.S., President, in the chair. — 

 T. W. Butcher: Structural details of Cosciiwdiscns aster- 

 oinpltalits. A paper describing the primary areolations with 

 the secondary and tertiary markings, illustrated by a series of 

 lantern slides made from photomicrographs obtained at a 

 magnification of one thousand one hundred. In addition 

 slides were shown demonstrating a fine siliceous network or 

 veil lying upon the outer surface of the valve, and others in 

 series, from photomicrographs taken, at five or six consecutive 

 foci, of the hexagonal cell layer with its " ringed " openings of 

 Morland, to prove that these openings are clear and not 

 obstructed by the finely perforated membrane recently 

 reported by Mr. Nelson ijourn. R.M.S.. October 1910). The 

 membrane being non-existent, its value as a test for a high- 

 power lens is nil. — Rev. Hilderic Friend: New British 

 Enchytraeids. Encliytraeits niiiiiinus Bret, was described in 

 the Rev. Suisse de Zoologie in 1S99. Michaelsen, in Das 

 Tierreicli, 1900, suggested that it might be one with 

 E. argenteus Mich. (= E. parvulus Friend). Bretscher 

 examined the subject again in 1902. and decided that the 

 two were distinct. The author, who had already described 

 E. argenteus. has found E. minimus at Buxton, and 

 holds with Bretscher. Fridericia peruviana n. sp. was 

 received in earth from Peru and submitted to the 

 author by the authorities at Kew. It is 5-6 nun. in 

 length, has 2-5 setae which are somewhat larger behind 

 than before. Brain slightly concave posteriorly : oeso- 

 phagus sharply marked off from intestine : dorsal vessel 

 postclitellian in origin with dilatations in segs. 7-9. Salivary 

 glands not branched; long. — Walter Bagshaw : Instantaneous 

 exposure in photomicrography. — Flashlight illumination has 

 been put to a novel use by Mr. Walter Bagshaw. F.R.M.S., 

 for the photography through the microscope of objects in 

 motion. A good negative of freshwater poly^^oa, iLophopns 

 crystalliniis) expanding its tentacles, was secured by a 

 charge of "Agfa Flashlight Powder" in one-thirtieth of a 

 second. Gatherings of Pond-life, such as diatoms, larvae, 

 water fleas, also yielded successful results. Provision was 

 made for replacing the ordinary lamp by flash powder put in 

 the position previously occupied by the centre of flame, .and 

 ignition made with a red-hot wire. 



ORNITHOLOGY. 



By Hi'Gn Bovi) Watt, M.B.O.U. 



BLACK REDSTART REPORTED NESTING IN 

 ENGLAND.— It is stated that the Black Redst.art (Rnticilla 

 titys^ has been identified as nesting in the Keswick district 

 this season (1911). Very conclusive and convincing evidence 

 is. however, necessary before this species can be admitted to 

 the list of British nesting birds. In past years supposed eggs 

 have been obtained or observations made in different localities 

 (Sherwood Forest, in 1854 and 1856; Dumfriesshire in 

 1858 and 1SS9. and Hertfordshire in 1876). but in no case has 

 the identification as to nesting been accepted as satisfactory. 

 The bird's habitat is central and southern Europe, and the 

 seasons of its annual occurrence in England are autumn and 

 winter, although in a very few instances it has been found at 

 other times. This distribution is rather curious, as it is 

 only a summer visitor in central Europe, and has not so high 

 a northern range as the Common Redstart (R. phoenicnrus), 

 which appears throughout all Europe in summer, and is not 

 known in the British Isles at any other season of the year. 

 The point is. that the summer Redstart in Britain is the more 

 northern species, but the visitant Redstart seen i[i autumn 

 and winter is the southern form (/?. fitys). 



THE STARLING AS A MIMIC— A correspondent, 

 Mr. Basil T, Rowsfell. writing from St. Martin's. Guernsey, 

 says that on 22nd September last he was astonished to hear 

 what was apparently a Wryneck's call from a tree in his 

 garden there, clear and distinct, as it may be heard in spring 

 and early summer. This was repeated for some days up to 

 6th October, and, by carefully watching. Mr. Rowsfell made 

 out that the calls came from a Starling {Stnrntis luilgaris). 

 He suggests that this particular bird may have been reared in 

 the immediate vicinity of a Wryneck's nest, and caught the 

 note from the parent Wrynecks. 



Starlings are, of course, well known as mimics. The wailing 

 whistle of the Common Curlew (the Whaup of northern 

 districts) is associated with wild and lonely places, but we 

 have known a Starling to give a very passable i[nitation of this 

 call from the house-tops of a great city. This individual bird, 

 or another which had also picked up the trick, returned to 

 the same place a second winter and brought moorland echoes 

 with it. amongst thronging people and crowded houses. 



THE NATIONAL COLLECTION AT SOUTH 

 KENSINGTON. — According to the "Return" presented to 

 Parliament of the British Museum for the year 1910, the 

 additions made to the great bird collections at the Natural 

 History Museum amounted to 9377 specimens in the year 

 named. These came mostly from Asia, .Africa and South 

 America, and several of the collections consist of some hundreds 

 of items. The most extensive is 1346 birds, nests and eggs 

 from .Angola. Portuguese Guinea, and the Cape Verde Islands, 

 obtained by Dr. W. J. Ansorge. 



IMlOTOGK.Al'HY. 



By Edgar Se.mor. 



The article in " Notes" of last issue contained a description 

 of the use of a pin-hole in place of a lens, and was illustrated 

 by an excellent photograph taken by its means. It may, 

 therefore, be of interest in connection with this subject, to 

 just consider "on theoretical grounds." the conditions which 

 govern the use of plain apertures, in order to obtain the best 

 results with them in practice. It is well known that 

 photographs taken by means of a plain aperture in place of 

 a lens, pos.sess advantages over those taken with the lens, 

 in .so far .as distortion is entirely absent, and the artistic effect 

 obtained is extremely pleasing. It is also well known that for 

 a given aperture an image will be obtained at whatever be the 

 distance from it to the plate ; but it was proved many years 

 ago by Lord Rayleigh. as a consequence of the Wave Theory 



