May. 1901.] 



KNOWLEDGE. 



117 



notice his varying success in efforts to reproduce some 

 woll-kuown cries of other coninion birds. — Chaulf.s A. 

 AViTCHEl-L, Clieltenhain. 



Xulcracier (h Sussfj- (Zooloqixl, Maivli, 1901, p. 107). —Mr. II. 

 Mariuiiduko L!»n2;iliile ivcord-i that a Nutfra.'ker was sliot on Di'Oi'm- 

 lior 21st. IS'OO. at Chilgivvf, iioar Chiohcstor. This bird was prubahlv 

 H straggler fiMm the iuvasion of tlic eastern form of the Xiitcraeker 

 into Scandinavia, Oennanv and Holland (see Kxowlbhok, Novem- 

 ber, 1900, p. 2o6L 



Ilairt/'plumafled Moorhens (Zooloffisf. Jlareh, 1001). — Mr. U. K. 

 Forrest has, during the last three years, examined live speeimens of a 

 singular variety of the Moorhen taken at various plaees near 

 Shrewrsburv. These birds were light yellowish-brown on the upper 

 parts, and very light grey undiTueath. 'J'he feathers, '' instead of 

 having the ]unna" uniti-J into a eompaet web, have them all separate, 

 especially on the exposed portion of each feather." The defect 

 exteuds to the flight feathers, so that the birds could not fly, yet they 

 seemed healthy. By a microscopic examination, Mr. Forrest found 

 that '■ the barbs and liooklets which, in ordinary feathers, cause tlie 

 pinnte to cling together in a compact web, are almost entirely absent 

 on the body-feathers ; whilst in the quill feathers many of the pinme 

 have barbs on one side, but no hookleta to hold them togetlier." 



Black-tailed Godirit in Co. Wexford (Irish Naturalist, April, 

 1891,p.9;t).— ilr. (>. E. IT. Barrett-Hamilton records tlial Black-tailed 

 Godwits were very ])lentiful at Kilmore, in Co. Wexfm-d, during 

 December and January last. This bird is an irregular visitor to 

 Ireland at any time, while in winter it has but rarely been observed. 



Jloneii Buzzard in Soltcai/ (Annals of Scott. Nat. lli.it., .Vjiril, 

 1901, p. 801. — In an article entitled " Zoological Notes from Sohvay." 

 Mr. Robert Service describes how his friend, Mr. Jardine, found a 

 Honey Buzzard on January 17th last. His collie dog ''set" l>v a 

 sheep trough, and a large " Hawk ' got up and Hew some forty yards. 

 Mr. Jardine followed, and witli no dilliculty caught the bird. It was 

 liberated in a baru,and tlicre ^Ir. Service saw if., and jjrouounced it t.o 

 be a " particidarly fine Honey Buzzard in the most splendid condition.' 

 The bird had no signs of escape from captivity and no wounds, yet it 

 was strangely tame, and allowed itself to be stroked. The appearance 

 of a dog, however, caused its whole aspect to change '' to a fierce and 

 lighting attitude." The Honey Buzzard is a great rarity in Solway. 



Barred Warbler in Barra (Annals of Scott. Nat. Hist., April, 

 1901, p. 114).— On October 29th, 1900, Mr. W. L. MacGillivray shot 

 a young Barred Warbler in Barra. This is but the third Scottisli 

 example, and curiously enough all have been obtained in the western 

 isles. 



Scops Owl in Shetland (Annals of Srof/ish Naf. Hist., -Vpi'il. 

 1901. p. 116).— In Knoh-i.edoe for August, 1900. p. 181, a bird of 

 this speries was noted to have been captured for the first tiiui' in 

 Shetland. Mr. Clarke now records that a second specimen was 

 obtained in the western part of the main island about the same time 

 as the first. 



AH contributiotis to the column, either in the way of notes 

 or photograplis, should be forwarded to Habry F. Witherby, 

 at 1, Eliot Place, Blacklieath, Kent. 



/ 



Conducted by >r. I.Cro§s 



Illumination with Artiikul Licht. — The lara|i that 

 has proved most universally satisfactory is the regular one sold 

 for microscopical work, with a i-inch or ^-inch wick, but to 

 many people this is objectionable for several reasons, the chief 

 of which is that with the general use of gas and electric light, a 

 mineral oil is not ke|)t in the house, excepting for this special 

 lamp : it also is not clean to handle, and requires a certain 

 amount of attention ; al.so it is not always immediately ready 

 for service when required. In laboratories such a lamp is out 



of the question, and bare gas jets, or g.is jets with upright 

 chimneys, are generally to bo fouiul. 



1 have recently been making some oxperiinents with gas 

 and electric lamps to see if some practical form of illnniinaiit, 

 always available for use without special preparation, cannot bo 

 devised for critical microscopical work. 



Two important considerations have to 1)0 kept in view, one 

 is that the liglit must bo brilliant, and the other is that it should 

 be possible to focus an image of the source of light l)y means of 

 the substage condenser, in the field of view. 



.\ very serviceable illumination can bo secured with the 

 AVelsbach' incandescent gas light, but the reticulations of the 

 mantle are an obvious objection, and the Hamo has too large a 

 surface. These can be overcome by means of a shade of metal 

 surrounding tlio chimney at a distance of three or four inches. 

 In this shade a small rectangular or circular .slot should be per- 

 forated. When working, this slot .would be treated as the 

 source of light and focussed accordingly. 



At a recent meeting of the Koyal Microscopical Society, Mr. 

 Housselet exhibited an incandescent electric lamp of the Kdison 

 and Swan " Focus" type, which has a somewhat coarse lilament 

 not unlike a corkscrew suspended horizontally in the bulb. 

 This lamp gives an intensely brilliant light, and it has on many 

 occasions been used for magic lantern purposes. It was recom- 

 mended that the light for microsco]iical work should bo taken 

 from the edge of the filament and focussed in the .same manner 

 as the wick of an oil lamp. The light arranged in this way was, 

 however, to my mind too much dill'nsod, notwithstanding that 

 a shade was used. On making further inquiry I tind that a 

 stand for an electric lamp is made for laryngological and aural 

 examinations wliich has joints and movements for .adjusting in 

 any desired position. In the usual tyjie it carries an ordinary 

 eight or sixteen candle-power lamp, but it will quite well carry 

 the " Focus " pattern. If now an enclosing shade be provided 

 similar to that described for the Welsbach bght above, with an 

 aperture which can be treated as the source of illumination, an 

 ideal electric light for microscopy is secured. This would 

 answer well also for photo-micrography. 



A lamp, somewhat similar to the foregoing, has been used by 

 me with considerable satisfaction, though long usage has created 

 a distinct prejudice in favour of the i.-inch wick oil lamp. 



All workers have not electric current available so this will not 

 appeal to them, lint the majority have gas, ami where oil lamps 

 are objected to, I would advise a trial of the Wclshach light 

 arranged as described above. 



PnoTo-MI(■R(>l^R.\^IIY with ARf Lamp. — Trouble is in- 

 variably experienced in maintaining the light in one central 

 position, and several devices have been resorted to in order to 

 control this. Xo automatic lamp is really useful for the purpo.se, 

 a hand-fed lamp must be em])loyed. When this is properly 

 .adjusted and the condensing lens is in position, a luminous disc 

 will Lie i=een upon the leaves of the partially closed Iris 

 diajihragm of the substage condenser. During an exposure it 

 will only be necessary to maintain this disc in a fixed position 

 by turning the milled head of the lamp very gently as re(niired, 

 and the light may be kept perfectly central for any length of 

 time. It is ])resumed that a horizontal camera would be used. 



St.unim; Fi.acki.la. — The pre|)aration of Bacteria so as to 

 exhibit flagella has always seemed to be unsatisfactory and 

 difficult. Very few workers are really successful and none have 

 produced permanent mounts. An interesting note occurs in 

 the Thompson Yates Laboratories Report, by Dr. MacConkey, 

 which deserves consideration. 



It has been considered essential when staining such prejiara- 

 tions to use a mordant, presumably to fix the dye in the 

 substance of the flagellum. It is suggested that the rendering 

 visible of the flagella in consequence of the use of the mordant 

 is not because of the etfect which it has hitherto been credited 

 with producing, so much as by causing the llagellum to swell 

 and become thicker. The flagella are of cxipiisite tenuity, so 

 much so, that when stained, the dyes do not seem to render 

 them visible to the same extent as when a so-called mordant is 

 used. The suggestion put forward is conlirmed by the state- 

 ment that the flagella appear to be thicker than they are 

 supposed to be actually, and the organisms them.selves are larger 

 after the use of a mordant than when stained in the ordinary way. 

 There are dyes which have the effect of staining the flagelhi 

 deeply an<l producing a thickening, but it is observed that, as 



