ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 721 



thoroughly dry, prepared at least forty-eight hours, and preferably 

 more, before using. It may be objected that so much drying con- 

 sumes too much time. Slides can be ringed at the rate of a gross an 

 hour, and this at odd moments when no other species of microscopical 

 work is possible. These slides, packed in rack boxes, occupy but 

 little space, are free from dust, and reliable slides are always ready 

 for immediate use. In deep cells for opaque mounts, it is not found 

 that those slides whose cells contain an aperture are any more free 

 from dewy deposits upon the cover than those which are hermetically 

 sealed. 



The following form of cell she has found very satisfactory. 

 Use no volatile substance within the cell ; paste a dead black paper 

 upon a white (not much glazed, and therefore absorbent) one, and 

 from this cut with a gun-punch disks of the desired size ; centre a 

 slide, and paste a disk upon it (black side down), to exclude the 

 light ; upon this cement with gold size a brass curtain-ring, flattened 

 or not, according to the depth of the cell required ; ruu on a back- 

 ground, with any shade of water-colour paint which best exhibits the 

 object, leaving a white margin around the edge of the cell ; cement 

 the cover with a small quantity of white zinc to the ring ; colour the 

 cell as may be desired ; run on the copal mixture [already described] 

 giving added security to the cover and rounding out the cell. This 

 makes a neat and durable mount, and no dewy deposits have ever, to 

 her knowledge, appeared upon the covers of cells so made. 



With regard to the prevention of " dewing " in transparent 

 mounts, she has found it essential that the objects should be 

 thoroughly dry. If diatoms, use the covers direct from the brass 

 mounting table ; or if such as have been breathed upon, as scales, see 

 that the moisture is fully evaporated, and in sealing, use the smallest 

 quantity of cement consistent with a perfect adhesion of the cover- 

 glass. 



Labelling Slides.* — It is suggested that a good plan is to punch 

 some squares or circles out of very thin talc ; cover the end of the 

 glass slip with a thin layer of gilder's whiting and gum-water ; when 

 dry, write on this with common ink, let it dry, put a very small drop 

 of Canada balsam upon it ; cover with a circle of thin talc, and allow 

 all to dry ; then clean the edges with benzole and water mixed. It 

 will not peel off or get dirty like printed labels. 



Slide Labels.t— Mr. E. H. Griffiths writes that " very beautiful 

 and very practical labels for Microscope slides may be quickly made 

 with the brush and pen. On the ends of the slides turn smooth discs 

 of good, clear white zinc cement, and with finishing colours border 

 to suit the fancy. With a pen, write or print on the white centre 

 whatever is desired." 



Cabinet for Microscopical Preparations.! — Prof. A. Eternod 

 describes the cabinet in use at the histological laboratory of Geneva, 

 as being especially suitable for large institutions. 



* The Microscope, v. (1885) p. 179. f Ibid., vi. (1886) p. 84. 



J Zeitscbr. f. Wiss. Mikr., ii. (1885) pp. 511-3 (2 figs.). 

 Ser. 2.— Vol. VI. 3 B 



