ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 743 



glacial and the Lydrated. For mounting, a saturated solution of 

 glacial boro-glyceride is used, made by dissolving tlie substance in 

 warm water — using about one part to twelve of water — and allowing 

 the surplus to crystallize out and settle. It is excellent for vegetable 

 tissues. It does not act on them in any way, grains of chlorophyll 

 even remain unchanged. It does not destroy the anilin colours used 

 for staining, although the delicate colours of flower petals appear to 

 bleach in the solution. It answers for mounting insects whole and 

 without pressure. Gold size or brown cement does for fixing the 

 upjier glass of the cell. 



Litharge and Glycerin as a Cement. — Mr. J. C. Douglas 

 writes that if sifted dry litharge powder is mixed with glycerin, 

 it forms a cement which hardens rapidly in air and water, bears 275^ 

 C, and is very resistant to reagents. It is stated to be adhesive to all 

 materials, the articles to be cemented being preferably moistened with 

 glycerin. The cement will probably be found well suited to many 

 purposes of the microscopist. 



Hamlin's Ideal Slide.* — Mr. F. M, Hamlin considers an " ideal 

 slide " to be one where the slide and cell are of one piece of glass, 

 thus doing away with all cement except that required to secure the 

 cover-glass. 



When a cell of ordinary depth is required, an excavation could be 

 made in a slide of usual thickness, which could not only contain the 

 object, but the cover-glass, so that the upper surface of the latter 

 should be even with the surface of the slide, thus protecting it from 



Fig. 178. 



being displaced by accident. (This plan was suggested by Mr. B. 

 Piffard last year. See this Journal, Vol. IV. (1884) p. 655.) The 

 diameter of the excavation for the cell should be a little less than that 

 for the cover-glass, so as to form a ledge for it to rest upon (fig. 178). 



When a cell of greater depth is required than an ordinary slide 

 will permit, a very different case is presented, unless a slide of unusual 

 thickness is used. To secure in the middle of the slide tlie necessary 

 thickness, the glass could be cast in a mould which would, at the 

 same time, form the cell and the ledge for the support of the cover- 

 glass (fig. 179). 



There are difficulties in the way of carrying out these ideas, but 



Fir;. 179. 



the author cannot think them insuperable, or, if overcome, that they 

 will render such slides too expensive for general use. 



Apart frf>m the saving of time and labour, the chief advantages 

 would bo in the perfect safety and imperishability of the mount, for 



• I'roc. Amor. Hoc. Micr. 71 b Ann. Meeting, 1884, i>\>. 170-80 (2 figs.). 



;} c 2 



