1883.] 



MICROSCOPICAL JOURNAL. 



151 



the cement ring, but in these cases it 

 is advisable to have a shallow cell. 

 Pollen-grains, having been allowed to 

 dry, and a slide with cell having been 

 prepared by being breathed upon, the 

 pollen-grains may be dusted upon the 

 slide, when the warmed cover-glass 

 will in this case also securely seal up 

 the object. For pure diatom gather- 

 ings or deposits that are desired dry, 

 it is only necessarv, after sufficient 

 cleaning and washing, to put a drop 

 of the fluid containing them upon a 

 cover-glass, and allowing this to dry, 

 not by heat, but quite spontaneously, 

 by warmiiig the slide and cell as de- 

 scribed for butterfly scales — the cover 

 may be pressed down and securely 

 fixed. 



Canada balsam, with its sticky 

 abominations, has now largely given 

 place to balsam and benzole, balsam 

 and chloroform, or damar, each of 

 which medium has advantages over 

 the other for certain objects ; but my 

 choice for general work is balsam and 

 benzole, which I have used for years, 

 and for a great many descriptions of 

 work. As an illustration of balsam 

 mounting, or rather mounting in bal- 

 sam and benzole, we will take some 

 objects from the animal kingdom — 

 say parasites. It will in most cases 

 be advisable to put them in liquor 

 potassi for a short time. When they 

 have been softened or sufficiently re- 

 duced in color, they must be well 

 washed in water, and if they are 

 brushed under water with a stiff camel- 

 hair pencil, the legs will frequently 

 be found placed right for mounting. 



The last washing water having been 

 poured off, and methylated spirit 

 added, let them remain in this for a 

 few hours, and then the spirit be re- 

 newed. After the lapse of a few hours 

 more, pour off the spirit and add oil 

 of cloves or cajeput. The latter is 

 quite equal to and much cheaper than 

 the clove oil. From this the object 

 may be placed upon a clean slide, and 

 any surrounding oil should be ab- 

 sorbed by blotting or filter paper; a 

 drop of balsam and benzole being 



placed upon it, the slide may be left 

 for a few seconds, and then a waimed 

 cover-glass put down, a clip placed 

 upon it, and the operation of mount- 

 ing is so far complete. The slide 

 now requires placing in a warm place 

 for a few days before the later finish- 

 ing touches can be applied to it. 



If it be Polycystina, Foraminifera, 

 Sponge or Gorgonia Spicules, or any 

 such object, that it is wished to mount, 

 a thin smear of gum should be placed 

 on one side of the centre of the slip, 

 when, if the thumb be drawn firmly 

 over the slide, a very thin, almost in- 

 ^■isible film will remain, which must 

 be allowed to dry. If then a small 

 heap of the dry material be put on 

 the centre of the smear, and the slide, 

 while held in the fingers at one end, 

 be gently tapped on the other by the 

 foreceps, or anything hard which hap- 

 pens to be handy, the material will be 

 seen to spread itself over the gummed 

 surface, and its disposal may, with a 

 little practice, be greatly controlled. 

 The slide now requires breathing 

 upon, and when again dry, a drop of 

 the balsam and benzole must be put 

 over the object, the cover-glass 

 warmed, put down, and held with a 

 wire clip. The slide should be gently 

 heated over a spirit-lamp until the 

 medium just begins to boil, when it 

 must be removed quickly to a moder- 

 ately cool spot. This boiling has the 

 effect of driving out the air from in 

 or around an object ; and should any 

 bubbles appear about the slide, they 

 will almost invariably disappear when 

 the slide is left in a warm place. 



In mounting starches in damar, for 

 polariscope, a similar plan may be 

 adopted to spread the material, but 

 in this case no gum is required, the 

 breath upon the slide being enough 

 to hold the granules as they move 

 over the slide. When the breath has 

 evaporated it is not at once advisable 

 to at once drop on the damar, but first 

 placing over the starch a clean cover- 

 glass, put at each edge of the cover, 

 but not exactly opposite, a drop of 

 damar, which running under the cover 



