ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 829 



dries slowly. By thinning the solution with strong alcohol the 

 resulting cement becomes all that can be desired. 



It is well to have two kinds of shellac cement always at hand — 

 one so thick that it will just flow from the brush on the turntable, 

 the other thinner. The first is useful for making cells, the second 

 as a general cement to attach covers, &c. 



Coating Diatoms with Silver.* — A. Y. Moore burns one side of 

 a diatom to the cover-glass and then coats the other side with pure 

 silver. The refractive index of silver according to Brewster is 3 • 27, 

 and the visibility of a diatom so prepared is four times as great as 

 when mounted dry, or more correctly, in the proportion of 1 • 84 to 

 •43. "The results obtained by giving such a visibility to the diatom 

 and at the same time utilizing the full aperture of the objective, can 

 hardly be imagined by one who has never S3en it. The dots upon 

 Amphipleura pellucida are shown in a way which would readily 

 convince those who still deny their existence. Even Rhizosolenia 

 alnta yields transverse lines which, so far as I know, have never been 

 seen by any other method." 



Lyon's Mailing Case.j — H. N. Lyon takes two slips of wood 3 by 

 1 in. and 1/16 in. thick, and in the centre of one makes a hole a little 

 larger than the cell. Paste a piece of stiff paper on one side of this 

 slip, covering the hole. Lay the slide between the slips and along 

 one side paste a piece of paper, not touching the glass slide however. 

 A rubber band holds the package tight, and it may be sent as it is or 

 first wrapped in pajier. If two or more slides are to be sent the 

 modus operandi is the same, except that the openings are alternately 

 on opposite sides. In this case the middle slips need not be covered. 



Action of Reagents in the discrimination of Vegetable Fibres.! — 

 V. Berthold classifies the more important vegetable fibres according to 

 the action upon them of iodine and sulphuric acid, as follows : — 

 A. Coloured blue, violet, or green by iodine and sulphuric acid : — 

 Flax, Chinese grass and ramie {Boehmeria nivea), roa (Ptp- 

 turus argentem), cotton, hemp, and sunn-hemp (Crotalaria 

 juncea). 

 I. Transverse sections coloured blue or violet, but showing no 

 yellow middle lamella ; cell-cavity usually filled with a 

 yellow mass. 

 a. Flax. Transverse sections occur either isolated or a small 

 number in a groiip ; the separate transverse sections are 

 not contiguous; they are polygonal, bounded by straight 

 lines, and have sharp edges. Lamination evident, blue or 

 yellow ; cell-cavity a yellow dot. Lou u;itudinal distortions 

 of the striaj indicated by darker lines which usually 

 cross. 



* The Microscope, iv. (1884) pp. 157-9 and 165. 

 t Ibid., p. 179. 



X Zcit.sclir. f. Wiircnkundf, 1883, pp. 14-5, 17-8 (16 figs.). See Bot. 

 Centntlbl., xvi. (1883J p. \iOH. 



