ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 509 



with the stems removed are invakmble. As to the kind of watch-glass 

 used, the author used the old-fashioned glass with fiat bottom taken 

 from obsolete watches. He procured quite a number, at the trifling cost 

 of a half-penny each, from a dealer in old silver, who broke the watches 

 up merely to get the silver from them. Some workers preferred to use 

 small tubes for staining purposes, but he found that much time was 

 wasted in extracting the sections from the tubes. To remove the 

 excess of water stain, the glasses may be gently lowered into a photo- 

 graphic dish filled with w^ater, and by the aid of a camel-hair brush 

 the sections may be cleaned and still be kept in the glass. On re- 

 moving the glass from the water, the excess may be drained off and the 

 alcoholic stain added. The sections stain better if allowed to remain a 

 long time in a weak stain, and the author found that for all practical 

 purposes (especially for photomicrography) the sections are better 

 stained after cutting than stained en bloc. The sections, after treat- 

 ment with methylated spirit or absolute alcohol, may be transferred to 

 the clearing medium, of which clove oil is the most commonly used. 

 Xylol is good, but takes a considerable time to act. Creosote has also 

 been recommended, but so far the author has not experimented with this. 

 If clove oil is used, it must be well washed out with xylol, otherwise it 

 seems to have a similar action on the balsam solution as glycerin has on 

 a varnish, that is, it retards the drying process. 



Mounting the Sections. — After clearing, the sections are ready to 

 mount in balsam. The author usually bought this in the crude state, 

 and dried it over a sand-bath, much to the disgust of other members of 

 the household, who objected to the odour. When hard, this may be 

 dissolved in xylol or benzole. He used the former, as most of 

 his sections were cleared in this — at any rate, all ribbon sections. The 

 cover-glasses and slips may be cleaned with potas. bichromate, or dilute 

 nitric acid ; the author generally used the latter. To the beginner he 

 recommends the thicker form of cover-glass at first, to get into the 

 habit of cleaning the glass without breaking it. The author's first 

 attempts in this direction were rather disastrous to his pocket, as he 

 started, ignorantly, with f in. circles of the thinnest variety, and spoilt 

 the greater part of the first half-oz. in acquiring the knack of holding 

 the circle without breaking it into many pieces. There are various 

 forms of cover-glass cleaners to be had, but so far he had not made 

 use of any. To ensure that the specimen remains in the centre of 

 the cover-glass, it is advisable to put a small drop of balsam on the 

 cover-glass, and, placing the specimen in this, to allow it to stand for some 

 hours, excluded from dust. When sufficiently dry, take a clean slip, 

 and place in the middle of the slide a drop of balsam. Now gently 

 lower the cover-glass by the aid of a needle on to the slip, and, if placed 

 in a slanting direction, the action of the descending cover-glass is such 

 that all air-bubbles are excluded. The slide should now be placed in 

 a slow oven, or allowed to stand for some days. Superfluous balsam may 

 then be cleaned off with a rag moistened with xylol, and, after 

 polishing, the sKde may be placed on a turntable and ringed with a 

 sable brush. For this purpose the author had a turntable mounted on a 

 wooden roller-skate wheel. The varnish he generally used was either 



