SCIENCE- GOSSIP. 



ing these small particles in xylol balsam it is best 

 to have ready a cover with a drop of solution 

 spread upon it. Having taken the material from 

 the bottom of the tube of xylol by means of a 

 pipette, bringing over as little as possible of the 

 liquid, it should be allowed to drop in the centre 

 of the cover into the balsam, which must be put 

 away to set. When mounting, this method will 

 prevent any of the small granules from being- 

 pressed from between the cover and slide. To 

 mount, warm the slide and apply a small drop of 

 balsam solution, press on cover carefully, and put 

 aside to harden. Ring with Bell's cement. — M. T. 

 Denne, 12 Guilford Street, London. 



Watson & Sons' Holoscopic Objectives. — On 

 p. 25 of the present volume of SciENCE-GossiP we 

 mentioned two new objectives of Messrs. Watson 

 & Sons' Holoscopic series, to which we must now 

 add a quarter-inch that has been recently sent us 

 for examination. This was stated to have a 

 numerical aperture of '93, but we found it to be 

 nearer -94. When we remind our readers that this 

 is equivalent to an air-angle of nearly 140°, it will 

 be seen that Messrs. Watson & Sons have succeeded 

 in making a lens which taxes the ability of an 

 optician to an unusual degree. We believe that it 

 is a matter of the greatest difficulty to make ob- 

 jectives of this power and aperture, and to make 

 them uniform ; but the performance of this objec- 

 tive leaves nothing to be desired. Its deiiuition is 

 excellent ; it was flat in the field, and it bore com- 

 paratively high eye-piecing well ; whilst the working- 

 distance, though of course not great, was sufficient. 

 We have now called attention to an inch of N.A. 

 •30, a half-inch of '65, a quarter-inch of '94, and a 

 one-sixth inch of '90, and await with interest two 

 oil immersions, of one-eighth and one-twelfth re- 

 spectively, of the same construction as the rest 

 of the Holoscopic series and of similar high aper- 

 tures. 



MEETINGS OF MICROSCOPICAL SOCIETIES. 



Quekett Microscopical Club. — Excursions, Septem- 

 ber 7th, East London Waterworks, from Totten- 

 ham (Hale) ; September 21st, Hale End for 

 Higham's Park, returning from Chingford. 



[For further articles in this number on Micro- 

 scopic subjects, see pp. 102, 105, 108, and 112.] 



EXTRACTS FROM POSTAL MICROSCOPICAL 

 SOCIETY'S NOTEBOOKS. 



[Beyond necessary editorial revision these ex- 

 tracts are printed as written by the various 

 members. — Ed. Microscopy, S.-G.] 



Carmine as a Stain. — Carmine is an excel- 

 lent stain, but if kept too long deposits a sedi- 

 ment {ante, page 91). It is best to filter through 

 Swedish filter paper before using. Picro-carmine 

 is a good stain, but the sections should be mounted 

 in Farrant's solution, in which case they improve 

 each year in colouring. I do not like Ehrlich's 

 stain. Folded sections are troublesome, but if 

 taken out of spirit and put into water, or vice 

 versa, they twist about and unfold beautifully. 

 Sections should always be floated, not dragged off 

 a section lifter. — John Swift Walker. 



Mounting Micro-fungi. — I see that Mr. Lett 

 (ante, pp. 27, 28) mounts his specimens in glycerine 

 jelly. The best medium for mounting micro-fungi 



is a mixture of acetic acid and glycerine in the- 

 proportion of 30 parts of acid to 100 of glycerine. 

 This formula was given me by Mr. Murray, of the- 

 Botanical Department of the British Museum, audi 

 I find it the very best that I have as yet tried.. 

 Of course there is the usual difficulty with air- 

 bubbles, and care must be taken to close the- 

 mounts securely. — A. Montague. 



I have never attempted to mount micro-fungi in 

 glycerine jelly. I may be wrong, but I think Y 

 prefer a slide which gives the little plant itself in. 

 situ, also the asci and elaters issuing from a 

 moistened specimen. That is the way I have- 

 always mounted my own slides, and they are as. 

 good now as they were when first done several: 

 years ago. I simply mounted them dry, taking 

 care that the asci were quite dry after being- 

 moistened, before putting on the cover-glass. It. 

 gives, I think, a better idea of the whole plant to- 

 have it, asci, and spores, all on the same slide, whilst 

 they are for the most part so minute that it is very- 

 easily done. — W. Jarrett. 



I have for years used the following medium for- 

 mounting moulds and fungi : gelatine, 1 part ^, 

 Water, 6 parts ; Glycerine, 7 parts ; Carbolic Acid,, 

 1 part. Warmed and filtered. — John Swift Walker,. 

 M.D. 



I frequently find forms similar to, but appa- 

 rently not identical with, Fusisporium roseolum 

 {ante, p. 28) in the sediment of impure drinking- 

 water sent me for analysis. The outer case or exo- 

 spores of many other varieties are frequently found, 

 in the same situation. — J. W. Gatclnim. 



Insect Anatomy. 



Except in classification, the English flies have- 

 had scant attention. We know comparatively little- 

 of the life-history of these common insects. Cer- 

 tainly the Rev. J. G. Wood did something in this- 

 way to make a few species popular, and Mr. B. T. 

 Lowne has given us a monograph on the anatomy 

 and physiology of the blow-fly ; yet the subject is 

 fai" from being exhausted. 



Sections of the Pitlvilli of Sarcophaga carnaria 

 (fig. 1). — These sections are somewhat vertically 

 oblique ; they should be vertical, but it is difficult . 



Fig. 1. PULVILLUS of Sarcophaga carnaria. 



to hit the exact plane when cutting so small am 

 object. In this fly the pulvilli are abnormally 

 large, and I have chosen it for that reason. The- 

 upper wall of the pulvillus is composed of chitinous 

 semi- or half-tubes directed lengthwise and joined 

 together at their edges, thus forming a very flexible 

 roof. The lower surface is clothed with fine taper- 

 ing, unpigmented hairs ; these hairs are usually 

 said to be hollow, but I have searched in vain to- 

 find a lumen in them. In some species the hairs- 

 are trumpet-shaped — e.g. gadfly and a parasite^ 

 from an Indian bat. In common with the pulvilli. 

 of other flies, I find they contain glands, but neither- 

 muscle nor nerve. These sections are very rich in 

 glands that evidently elaborate the viscid fluid by- 

 which the fly is enabled to walk in an inverted! 



