CHAPTER VII. 



SLIDES AND COVER-GLASSES ; MOUNTING ; ISOLATION, 

 SECTIONING BY THE COLLODION AND THE PARAF- 

 FIN METHODS ; LABELING AND STORING MICRO- 

 SCOPICAL PREPARATIONS ; EXPERIMENTS IN MICRO- 

 CHEMISTRY. 



APPARATUS AND MATERIAL FOR THIS CHAPTER. 



Microscope, compound and simple (Ch. I) ; Micro-Spectroscope and polariscope 

 (Ch. VI) ; Slides and cover-glasses (g 219-220) ; Cleaning mixtures for glass ('$ 227) ; 

 Alcohol and distilled or filtered water (§ 222) ; fine forceps for handling cover- 

 glasses ($ 222-226) ; Old handkerchiefs or lens paper (£ 107, 223). Paper boxes for 

 storing cover-glasses ($ 223, 225) ; Cover-glass measurer (Figs. 120-122) ; Mount- 

 ing material, — Farrant's solution, glycerin, glycerin-jelly and Canada balsam ($ 243, 

 246) ; Centering card and card for serial sections (§ 236) ; Material for dissociation 

 and for the paraffin and collodion method (§ 244) ; Material for paraffin and collo- 

 dion sectioning (# 250) ; Net-micrometer for arranging minute objects like diatoms 

 (? 3 l 7) ! Labels (g 309) ; Carbon ink for writing labels (# 295) ; Writing diamond 

 (3 2 95) ! Shellac cement ($ 316) ; Cabinet (§ 296) ; Re-agents for experiments in 

 micro-chemistry (§315). 



SLIDES AND COVER-GLASSES. 



§ 219. Slides, Glass Slides or Slips, Microscopic Slides or Slips. 



These are strips of clear flat glass upon which microscopic specimens 

 are usually mounted for preservation and ready examination. The size 

 that has been almost universally adopted for ordinary preparations is 25 

 x 76 millimeters (1x3 inches). For rock sections, slides 25 x 45 mm. 

 or 32 x 32 mm. are used ; for serial sections, slides 25 x 76 mm. , 50 x 75 

 mm. or 37 x 87 mm. are used. For special purposes, slides of the nec- 

 essary size are employed without regard to any conventional standard. 



Whatever size of slide is used, it should be made of clear glass and 

 the edges should be ground. It is altogether false economy to mount 

 microscopic objects on slides with unground edges. It is unsafe also as 

 the unground edges are liable to wound the hands. 



§ 220. Cleaning Slides. — For new slides a thorough rinsing in clean 

 water with subsequent wiping with a soft towel, and then an old soft 



