ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 161 



on the tiniest drop of water. On each cover let an object be arranged 

 in a moderately convex drop of balsam, extending to but not over the 

 edge of the cover. Then put the specimens away for the balsam to dry 

 for at least twelve hours in a dust-proof box. 



"When the covers have been exposed long enough, they may be turned 

 over on to warmed slides, but must not themselves be warmed first. 

 The danger of large air-bubbles is diminished by placing or smearing 

 a little fresh balsam on the slide, and this must be done if there is not 

 enough balsam on the cover. If possible, the cover should be held in 

 a pair of forceps and lowered horizontally over the slip, not on one 

 side first. It is then less liable to tilt, and the fresh balsam is squeezed 

 out symmetrically round the edge on pressing the cover down, and can 

 mostly be at once taken off with a knife, and the slide then cleaned 

 with spirit, the part under the middle of the cover being filled with the 

 exposed balsam, which is generally firm enough to keep from slipping. 

 Tn any case, the small amount of soft balsam around the edge will soon 

 dry after the rough scraping, thus avoiding the long waiting required 

 before cleaning slides mounted in the usual way. 



For mounting arranged objects, we may proceed as follows : — The 

 cover being stuck by breathing to a slip as before, the objects are all 

 neatly arranged on it in the layer of balsam, which should not be too 

 thick. The cover must now be exposed till the balsam is nearly or 

 quite hard — a week's exposure or longer may be requisite. The covers 

 must be turned over on to a cold slip into a drop of soft balsam and 

 pressed down, the objects being fixed in their places on the cover by 

 the hardened balsam, which is undisturbed. Scrape off the superfluous 

 soft balsam, and put away to dry. The streaky appearance due to the 

 two densities of balsam will soon disappear. 



The author has tried the above methods with great success for 

 mounting whole insects, and parts of insects, under pressure. For 

 preparing w^hole insects for mounting, it is best to soak in potash, wash 

 in water with a few drops of acetic acid, flatten out with two pieces of 

 glass, which are tied together while the specimen is soaked for a further 

 period in acidulated water, then in alcohol. Untie the glasses, float 

 the insect on to a cover-glass and take it out, drain off superfluous 

 alcohol, lay the cover on a slip, add a drop of clove-oil, which will 

 permeate the object, and the alcohol will mostly evaporate in half an 

 hour or more. Most of the superfluous clove-oil may then be drawn off 

 with a pointed tube and the balsam applied. Parts of insects may be 

 lifted from the alcohol into a vessel containing clove-oil, and afterwards 

 taken out and laid out in the balsam on the cover. In this way he has 

 mounted twelve parts of a honey-bee neatly grouped on one cover, and 

 several other " typo " slides, and he thinks it will be found that these 

 methods remove the chief difficulties of mounting in balsam, and 

 especially of mounting arranged slides. 



Buff ham, T. II.— [Arranging Slides.] Engl. Afcch., XL VI. (1887) pp. 39G-7. 



(6) Miscellaneous. 



Dissecting Dish.* — The following is taken from one of a series of 

 articles on " the Naturalist's Laboratory " in course of publication in 

 the journal noted at foot. 



* Knowledge, xi. (1887) pp. 278 (1 fig.). 

 1888. M 



