EMBEDDING 



651 



celloidin sections with any great degree of certainty thinner than 

 10ft to 15 p.. The parafin method is also to be selected for the 

 rapid preparation of tissues for sectioning, but it is only applicable 

 to small pieces of tissue. For large pieces better results will be 



c I d 



D 



c' 



d' 



II 



/' e' /' 



FIG. 462. A METHOD OF PREPARING A PAPER BOX FOR PARAFIN EMBEDDING. 

 I. A slip of paper, A, B, D, C, is folded, both ways, on the lines a-a', b-b', c-c ( ', and 

 d-d'. Then being folded into the form shown in II, it is laid flat, the section a, a', 6', 6, 

 shown in I, being uppermost, and the paper is creased on the lines e-e' and f-f. It is 

 then opened, folded in the shape of a box,/, ,/', <?', forming the bottom, and is secured 

 by folding down the ends after creasing the paper on the lines e-f and/-e'. 



obtained with celloidin. Many methods for the employment of 

 parafin have been extolled ; the following can be recommended. 

 The tissue, after fixation, should have been hardened in alcohol. 



1. Dehydrate in absolute alcohol twenty-four to forty-eight 

 hours ; very small pieces of tissue (1 to 2 mm,) may be completely 

 dehydrated in three to six hours. 



2. Place in equal parts of absolute alcohol and xylol, one to 

 three hours. 



3. Place in pure xylol until clear and translucent, one-half to 

 two hours. (For relatively large pieces of tissue cedar-wood oil or 

 pure anilin oil may be substituted for the xylol.) 



4. Place in melted parafin containing a little xylol ; that which 

 has been previously used for embedding does very well. 



5. Transfer to pure melted parafin. 



