CHAPTER VII 



SLIDES AND COVER-GLASSES ; MOUNTING ; ISOLATION ; 

 SECTIONING BY THE COLLODION AND THE PARAF- 

 FIN METHODS ; LABELING AND STORING MICRO- 

 SCOPICAL PREPARATIONS ; REAGENTS 



SLIDES AND COVER-GLASSES 



\ 234. 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 76 mm. or 37 x S7 mm. are used. For special purposes, slides 

 of the necessary 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. 



For micro-chemical work Dr. Chamot recommends slides of half the length of 

 those used in ordinary microscopic work. From the rapidity with which they are 

 destroyed, he thinks the ground edges are unnecessarily expensive. He adds 

 further: "It is a great misfortune that the colorless glass slips used in America 

 and so excellent for ordinary microscopic work should be easily attacked by all 

 liquids ; even water extracts a relatively enormous amount of alkalies and alka- 

 line earths. The slips of greenish glass, while not as neat or desirable for general 

 microscopy, seem to be decidedly more resistant, and are therefore preferable." 

 Transparent celluloid slides are recommended by Behrens for work where hydro- 

 fluoric acid and its derivatives are to be examined. (Chamot, Jour. Appl. Micr. 

 vol. iii, p. 793). 



\ 235. Cleaning Slides. — For new slides a thorough rinsing in clean water with 

 subsequent wiping with a soft cloth like glass toweling, or thin cotton cloth like 

 bleached cheese cloth (bunting or gauze, or absorbent surgical gauze), usually fits 

 them for ordinary use. If they are not satisfactorily cleaned in this way, soak 

 them a short time in 50% or 75",, alcohol, let them drain for a few moments on a 

 clean towel or on blotting paper, and then wipe with a soft cloth. In handling 

 the slides grasp them by their edges to avoid soiling the face of the slide. After 

 the slides are cleaned they should be stored in a place as free as possible from 

 dust. For storing, covered glass dishes are best. L'se museum jars or glass boxes 

 (Fig. 150). 



