45 



Time Required for Fixation. This varies according 

 to the size of tissues and fixative, but the necessary time 

 can always be determined by cutting through one of 

 the pieces. If the tissue is opaque throughout, it is 

 a sign that fixation is complete. The tissue should then 

 be removed and washed. (Vide ch. xxxiv.) 



Embedding Apparatus. A slab of metal (copper), 

 12 x 3 x f inches. Heat this at one end, and place 

 the vessel containing the paraffin at a point on the 

 slab where the paraffin is just kept melted. This is 



Fig. 12. Simple Embedding Apparatus 



the temperature for embedding. This simple device 

 serves all the purposes of an elaborate paraffin oven 

 (Fig. 12). 



Microtome. The Cambridge rocking microtome 

 (5), or the Minot (12) are the most convenient, but 

 sections can be quite well cut with cheaper instruments, 

 e.g., the Jung (i ios.). 



Razors. These may be hollow-ground on one 

 side, or on both, to a varying depth. For general 

 use a moderately hollow-ground razor is used. Examine 

 the edge under a low power to see if any notches exist 

 if so they must be ground out on a hone. A Belgian 

 stone, as long as possible, should be used and kept free 

 from grit during use. The stone should be soft, 



