THE MICROTOMIST'-S VADE-MECUM. 



CHAPTER I. 

 INTRODUCTORY. 



1. The General Method. The methods of modern microscopic 

 umitomy may be roughly classed as General and Special. 

 There is a General or Normal method which consists in care- 

 fully fixing the structures to be examined, staining them 

 with a nuclear stain, dehydrating with alcohol, and mounting 

 series of sections of the structures in balsam. It is by this 

 method that the work is blocked out and very often finished. 

 Special points are then studied, if necessary, by Special 

 Methods, such as examination of the living tissue elements, 

 in situ or in "indifferent" media; fixation with special fixing 

 agents ; staining with special stains ; dissociation by teasing 

 or maceration ; injection ; impregnation ; and the like. 



There is a further distinction which may be made, and 

 which may help to simplify matters. The processes of the 

 preparation of tissues may be divided into two stages, Pre- 

 liminary Preparation and Ulterior Preparation. Now the 

 processes of preliminary preparation are essentially identical 

 in all the methods, essential divergences being only found in 

 the details of ulterior preparation. By preliminary prepara- 

 tion is meant that group of processes whose object it is to 

 get the tissues into a fit state for passing unharmed through 

 all the ulterior processes to which it may be desired to submit 

 them. It comprehends the operations of (1) killing; (2) 

 fixing ; (3) the washing and other manipulations necessary 

 for removing the fixing agent from the tissues, and substi- 



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