THE FREEZING MICROTOME 



19 



using paraffin as a cement. A piece of stout copper or brass wire 

 is bent as indicated, pointed, and driven into an ordinary awl- 

 handle. Paraffin wax possesses the very valuable property of 

 remaining solid at ordinary temperatures, not cracking in the cold, 

 of winter nor softening in summer. It is unaltered by most re- 

 agents, is easily rendered fluid, and quickly solidifies. As a 

 cement, it is invaluable to the microscopical technologist. 



Fig. 13 indicates the method of cementing a piece of tissue to a 

 cork or other support. The tissue having been properly placed, 

 the wire tool is heated for a moment in the alcohol flame, and then 



FIG. 14. CATHCART'S ETHER FREEZING MICROTOME. 



touched to a cake of paraffin. The paraffin is melted in the 

 vicinity of the hot wire, a drop adheres to the latter and is carried 

 to the edge of the tissue. In the cut the wire tool is seen in the 

 position necessary for cementing one edge. The wire being 

 removed, the wax immediately cools and becomes solid. The other 

 sides are afterward cemented in like manner. The whole is done 

 in less time than is necessary to the description of the process. 



THE FREEZING MICROTOME 



After freezing a piece of tissue, sections may be cut without the 

 delay required for imbedding in paraffin or celloidin. Fresh tissues 

 may be used, or those hardened by some of the various fixing 



