196 BACTERIOLOGICAL DIAGNOSIS. 
retained in place by a clamp and appear in the same 
position as that occupied by the mass of frozen gum; as 
the paraffin is not sufficiently hard to be gripped by this 
clamp they must first be mounted on a piece of wood of 
a suitable size and shape. This can be cut out of a 
piece of firewood, and should have one surface left 
rough; this surface must be dipped in melted paraffin, 
and the under surface of the block partially melted in 
the flame and pressed firmly upon it. The piece of 
wood is then to be placed in the jaws of the clamp and 
the screw tightened up. 
Fic. 33.—Clamp for holding wooden block with the paraffin block. 
In the Cambridge Rocker and in some other forms of 
microtomes the sections adhere to one another at the 
edges and form long ribbons as they are cut. In the 
Cathcart microtome this is not the case, and each 
section must be dealt with separately; it is to be 
removed carefully from the knife blade with a camel’s 
hair brush or a finely pointed pair of forceps and placed 
upon the surface of a bowl of water just hot enough to 
warm the paraffin without melting it. When this is 
done the sections will spread out and lose all the creases, 
and are then ready to be mounted on slides or cover- 
glasses. 
