April, 1905. 



KNOWLEDGE & SCIENTIFIC NEWS. 



93 



likewise seen. A certain number of flat, oblong cells 

 from the parenchyma are always found in papers made 

 from straw, and ring-like portions of spiral and annular 

 vessels may also be found, but the most characteristic 

 features are the numbers of finely-serrated epidermal 

 cells, which are thick-walled with jagged edges. They 

 must, however, not be confused with the somewhat 

 similar cells in esparto. 



[To be Concluded.) 



R.oya.1 Microscopica.1 Society. 



February 15, at 20, Hanover Square, the President, 

 Dr. Dukinfield H. Scott, F.R.S., in the chair, the 

 Secretary read Mr. Finlayson's description of the Ashe- 

 Finlayson Comparascope. This is an apparatus designed 

 to show two images side by side in the microscope 

 for comparison, and consists of the attachment to any 

 ordinary microscope of a second objective, stage, and 

 illuminating apparatus, placed on one side at right angles 

 to the optical axis of the microscope. On the nosepiece 

 of the latter is screwed a short tube with a circular 

 aperture at one side, and containing a reflector extending 

 half-way across, placed at an angle of 45° to the axis 

 of the tube. The subsidiary apparatus is applied at this 

 aperture, the reflector thus transmitting the image of the 

 second slide to the eye-piece. The reflector utilises half 

 the diameter of the tube, the other half serving for the 

 passage of light from the primary objective direct to the 

 eyepiece. A diaphragm or division plate extends up 

 the tube from the reflector almost to the eyepiece to pre- 

 vent overlapping of the images, which appear together as 

 two semicircles, equally distinct. Mr. C. Beck exhibited 

 a new optical bench for microscopic illumination, photo- 

 micrography, micro and lantern projection, and a large 

 micro-photographic and enlarging camera, both bench 

 and camera being mounted on special tables. Mr. J. E. 

 Stead, F.R.S., delivered the first part of a lecture on 

 "Practical Micro- Metallurgy." He alluded to Dr. 

 Sorby's pioneer work on this subject some forty years 

 ago. Dr. Sorby's method was very simple, a small 

 piece of metal being ground down to a flat surface, and 

 finally polished on various grades of emery-paper, finish- 

 ing with rouge parchment. This method was still adopted, 

 but by means of special machinery the process was 

 reduced from two or three hours to five minutes. Mr. 

 Stead described this machinery, and explained the various 

 processes of cutting, grinding, and polishing, also the 

 different methods of preparing the polished surface so as 

 to render the structure visible, their mounting, and also 

 suitable illumination. The lecture was illustrated both 

 by lantern slides and by actual specimens, the beautiful 

 colours due to heating being shown in a quite novel way. 



The Quekett Microscopica.1 Club. 



The 42otli ordinary meeting, which was also the 

 annual meeting, was held on February 17 at 20, Hanover 

 Square, the President, Dr. E. J. Spitta, V.P.R.A.S., in 

 the chair. The annual report and balance sheet were 

 read, and gave evidence of a larger membership and im- 

 proved financial position as compared with the previous 

 year, the number of new members elected during the 

 year being 50, whilst the total membership amounted to 

 382. Dr. E. J. Spitta was re-elected President, and all 

 the other officers were also re-elected, except that Mr. 

 J. J. Vezey, F.R.M.S., was elected as a Vice-President 

 instead of Mr. George Massee, F.L.S., who retires. Mr. 

 A. D. Michael, F.L.S., delivered the annual address, 



dealing with " Improvements Effected in Modern Objec- 

 tives," with special reference to the various corrections 

 necessary for both objectives and eyepieces, the use of 

 Jena glasses, and their results, as evidenced in the 

 apochromatic lenses and the improvement in achromatic 

 lenses, which justify their description under a new name as 

 semi-apochromatic. 



Notes and Queries. 



Bausch and Lomb's Portable Microscope. 



With reference to my notice last month of this microscope, 

 and my remark that in the instrument sent me the condenser 

 did not quite come into focus, I am informed that this is pur- 

 posely put out of focus to prevent the upper and auxiliary 

 diaphragm being damaged by accidentally coming in contact 

 with the condenser top, and that by means of a screw thread 

 in the condenser mount the optical part can, if required, be 

 brought level with the stage. But as it is a primary require- 

 ment that a condenser should readily focus, it seems to me 

 that this is an undeserved concession to careless workers, the 

 more so as the upper diaphragm and the condenser are not 

 generally used together. A preferable way, if the upper 

 diaphragm is retained, would be to alter the construction of 

 the condenser so as to give it a slightly longer focus. In the 

 meantime, it is only fair to Messrs. Bausch and Lorab to add 

 this explanation. 



C. A. Wineku'orth {Brighton). — I think that from your de- 

 scription there can be little doubt that what you have observed 

 was merely an amceba undergoing division. Under any cir- 

 cumstances, they could not be bacteria. 



Dr. ir. /. Blanch (Si. Kitts). — Your question touches on a 

 matter which has exercised many minds, but only through a 

 misapprehension of the true principles involved. Assuming 

 that you could have a film that showed no grain under the 

 highest magnification, you could, of course, easily enough 

 magnify an image photographically impressed upon such a 

 film, and repeat the process as often as you wished, but in 

 each stage you would be merely magnifying what existed on 

 the original film. Now what you had upon the first film de- 

 pends on the aperture of the lens through which the photo- 

 graph was taken — in other words, the aperture of the lens 

 governs its resolution, and you would get no more detail by 

 subsequent magnification. So that the mere fact that you 

 enlarged a fine, but perfectly distinct, line into a broad and 

 coarse one would be useless. The experiments you allude to 

 tend to make fine detail resolved by the objective more evident 

 to the eye, but that does not affect the issue. 



Miss F. Elliot (Staines).--! much regret that pressure on 

 my space prevented my answering your query last month. 

 Hircinia variabilis is a horny sponge, very variable in shape, 

 as its name implies. The simplest forms are incrusting. hori- 

 zontally expanded, and more or less cake-shaped. It often 

 grows more vertically than horizontally, and attains an irregular 

 globose form. Sometimes, owing to uneven rapidity of growth, 

 rugose, tubercular, or even lobose forms are produced, but in 

 any case the sponge appears as a crust from the upper surface 

 of which these processes arise. The crust is sometimes much 

 curved, raised in the centre, and attached at the margins only. 

 The surface is covered with conuli, the oscula are large and 

 conspicuous, and the colour light to dark brown in the living 

 state. The sponge consists of slightly fascicular main fibres, 

 joined by connecting fibres which form a mesh or net-work. 

 There are several varieties, several of which are found in the 

 Adriatic, and it is found also in the Pacific Islands, India, 

 .Australia, Jamaica, Florida, &c. For the hfe history of sponges 

 I am afraid I must refer you to any good book on Zoology, 

 and unless I know more exactly what you wish specially to 

 examine I can scarcely advise you as to methods. You might 

 begin with a little dissecting, and then cut sections by hand. 

 '• Knowledge " is the only English journal which deals 

 systematicallv with Microscopy, and I regret with you that the 

 space at my disposal is not larger, but I will gladly give you 

 any assistance in my power. 



[Communications and enquiries on Microscopical matters are invited, 

 and should be addressed to F. Shillington Scabs, "Jersey," 

 St. Barnabas Road, Cambridge.] 



