THE MICROTOMIST'S 

 VADE-MECUM. 



PART I. 



CHAPTER I. 



INTRODUCTORY. 



1. The General Method. The methods of modern microscopic 

 anatomy may be roughly classed as General and Special. There is 

 a General or Normal method which consists in carefully 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, Preliminary 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 prelimi- 

 nary preparation 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 substituting for it the preservative 

 liquid or other reagents which it is desired to employ. Ulterior 

 preparation comprehends the processes sketched out in 3 et seq. 



2. Preliminary Preparation. The first thing to be done with any 

 structure is to fix its histological elements. (This statement 

 applies equally to all classes of objects, whether it be desired to cut 

 them into sections or to treat them in any other special way.) Two 



M. 1 



