28 



SCIENCE- G OSSIP. 



conducted by f. shillington scales, f.r.m.s. 



Pro-thallium op Lycopodium Clavatum. — 

 A recent number of the " Journal " of the Royal 

 Microscopical Society summarises a contribution 

 by Mr. W. H. Lang in the " Annals of Botany," 1899, 

 pp. 279-317, in which he describes and illustrates 

 the hitherto unknown prothallium of this club- 

 moss. It is a nearly flat plate of tissue, with 

 numerous rhizoids, its structure closely resembling 

 that of L. annotinum. Of seven prothallia examinee!, 

 six were female and one male. No archegones 

 were found on the latter, but on two of the female 

 prothallia a few antherids were seen. The 

 archegones and antherids were both confined to 

 the upper surface of the prothallium ; each organ 

 developed from a single cell. In the young plant 

 no structure was recognised comparable to the 

 protocorm of L. cernum. The large foot persists 

 for a considerable time after the prothallium has 

 disappeared. The cells of the prothallium are in- 

 fested by an endophylic fungus. The author then 

 discusses the comparative structure of the pro- 

 thallia of species of Lycopodiivm at present known, 

 and dissents from the view of Bruchmann that they 

 should, on this ground, be split up into a number 

 of distinct genera. 



Beck's New ^-Ietch Immersion Objective. — 

 Messrs. R. & J. Beck, Limited, have sent for our 

 inspection a new i-inch homogeneous oil-immer- 

 sion objective which will, we think, prove specially 

 useful to histological students and those workers 

 who do not require a high aperture. The N.A. of 

 this lens, like Messrs. Beck's cheaper i-inch, is 

 only 1 -0 ; but its definition is very good, whilst its 

 price, inclusive of oil, is only £3. We think it 

 should be a popular lens, as it is much superior to 

 the water-lenses often used of this power, though 

 a water-lens has facilities and advantages attend- 

 ing its use that make it of service to many workers, 

 especially when dealing with mounts made rapidly 

 for temporary examination only. The objective 

 has a good working distance, and is corrected for 

 the short tube length. 



Section of Limestone Mr. Mason, of Park 



Road, Clapham, has recently sent us an exception- 

 ally interesting microscopical slide of a section 

 of Carboniferous Limestone from Llanynynech, 

 Montgomeryshire. This section is peculiarly rich 

 in organic remains of unusual variety, and has, we 

 believe, called forth some diversity of opinion 

 amongst those interested in the subject. Apart 

 from this, the slide is a really beautiful one, and 

 we recommend it to the notice of those of our 

 readers who may be concerned with such matters. 



Swift's New Bacteriological Microscope. — 

 Messrs. James Swift & Son have recently brought 

 out and exhibited before the Royal Microscopical 

 Society a new microscope for bacteriological pur- 

 poses that differs in some ways from the model 

 hitherto adopted by this firm. *The coarse adjust- 

 ment rack works in a circular groove instead of the 



usual angular one, this being the arrangement 

 largely used abroad, whilst the fine adjustment is 

 also of the Continental triangular bar form. The 

 drawback to this type of fine adjustment is that it 

 necessarily bears the whole weight of the body of 

 the instrument, and Messrs. Swift have therefore 

 improved on the Continental form hitherto made 

 by the use of their patent differential screw. The 

 milled head of this last is so divided that one 

 division equals -003 millimetre, and the index can be 

 shifted to zero to allow of direct readings being made. 

 The draw-tube is graduated in millimetres, and 

 varies the tube-length from 160 mm. to 220 mm. The 

 stage is covered with vulcanite, and is of specially 

 ample size to allow of the use of the largest petric 

 dish, without any risk of the plate slipping off the 

 stage. The right-hand side of the stage is divided 



Ba< teriologkal Microscope. 



into squares as a finder, which enables the ob- 

 server to record the position of a slide for future 

 reference. A full-sized improved Abbe condenser 

 with iris diaphragm beneath the stage is focussed 

 by means of a special spiral focussing adjustment 

 that has proved both convenient and easy of mani- 

 pulation. The base of the stand is Messrs. Swift's 

 well-known claw-tripod, giving freedom of mani- 

 pulation combined with stability ; and this form of 

 base is greatly to be preferred to the ordinary 

 Continental horseshoe and pillar form. The price 

 of the microscope as described and illustrated, 

 with one eyepiece, Abbe condenser with iris dia- 

 phragm, dust-proof triple nose-piece, § inch, |, and 

 T X 2 oil immersion- — all of Messrs. Swift's well-known 

 and excellent " Pan-aplanatic " series — -and case is 

 £T6, or without the ^immersion £11. This micro- 

 scope has been submitted to our personal inspec- 

 tion, and we can recommend it to the notice of 

 our readers. 



