72 MOUNTING AND PREPARATION OF OBJECTS. 



upper surface of the specimen is flattened with a 

 file, next rubbed down on a perfectly flat Arkansus 

 stone ; and finally polished with putty powder 

 spread on a leather pad; a simple microscope is 

 useful for watching the progress of the latter oper- 

 ation. When finished this side is fastened on the 

 wood; the specimen filed down as thin as possible, 

 and the foregoing process repeated. 



If the specimen is very brittle it is best attached 

 to a glass slip, and saturated with balsam, before 

 commencing operations on the second surface. 



The finished section may be now removed from 

 the wooden support by soaking in turpentine, after 

 which it is transferred to clove oil, and then to ab- 

 solute alcohol. On removal from this the alcohol is 

 allowed to evaporate spontaneously, and the section 

 mounted dry or in balsam. 



For the preparation of injected specimens and 

 other processes, we refer the reader to the authori- 

 ties already mentioned, reminding them of the fact, 

 that violet and blue solutions are unsatisfactory for 

 staining or injecting sections intended for photo- 

 graphy, and also that only two methods of mounting 

 namely, in gum and glycerine, and dry, are re- 

 quired for any preparation within the domain of 

 microscopy. 



The secret of successful mounting is cleanliness ; 

 all solutions must be filtered before and after using ; 

 specimens, while in them, should be covered with a 

 bell jar; and all media should be kept in wide mouthed 

 bottles, closed by glass caps, not corks or stoppers. 



