108 A MANUAL OF BACTERIOLOGY 



by Cheatle for infiltrating under diminished pressure, is 

 made by Messrs. Hear son. 



In order to prepare sections from material embedded in 

 paraffin some form of microtome must be employed. An 

 ether-freezing microtome can be made use of with some 

 manipulation, the paraffin block being placed in a little 

 melted paraffin on the freezing plate so that it is cemented 

 there, and sections are cut with the razor or plane iron, 

 as though it had been frozen (it is not to be frozen). It is 



FIG. 21. Cambridge rocking microtome. 



better, however, to use some special form of microtome, 

 the Cambridge " Rocker " (Fig. 21), or a modification of 

 it, or the " Minot," being perhaps the best. The block of 

 paraffin containing the tissue is trimmed with a knife to 

 remove the excess, and is cemented to the carrier of the 

 microtome with a little melted paraffin or by melting 

 the paraffin on it with a hot iron (end of a file, etc.) or a 

 match. The union may be made more secure by melting 

 the paraffin around the base of the block with a hot iron. 



Having fixed the paraffin block to the carrier, sections 

 may then be cut of any degree of thinness. It is essential 



