MICROTOMES 93 



do this it is essential for the knife or razor to have a keen 

 edge and one of the right nature, for a knife may be 

 perfectly sharp and yet the sections as they are cut may 

 roll up in such a manner that it is difficult to flatten them. 

 Though this may be due to a wrong consistence of the 

 paraffin, owing to cold weather or some other factor, in 

 the majority of instances it is the edge of the knife which 

 is at fault. Provided the knife be sharp, stropping on 

 the palm of the hand will usually remedy this difficulty. 

 The paraffin being of the right consistence, and the knife 

 in good order, the sections as they are cut should be flat 

 and should adhere together at adjacent margins so that 

 a ribbon of greater or shorter length is formed. 



Satisfactory sections having been obtained, they are 

 transferred with a needle or camel's-hair brush to a tin 

 pan containing a little water, or spirit and water warmed 

 to about 40 C. The sections float and the paraffin softens 

 so that they spread out perfectly flat (the water must 

 not be hot enough to melt the paraffin). A clean slide is 

 then introduced underneath the section, raised so that 

 the section is lifted up on it, and by fixing the section with 

 a needle and tilting the slide the section is deposited in 

 the required position on the slide and allowed to dry. 

 If preferred, the section may be transferred to a slide 

 flooded with water, which is warmed over the Bunsen. 

 The slides can be manipulated in an hour or two if dried 

 at 37 C., but it is best to allow them to dry in the incubator 

 all night. It will be found after this treatment that thin 

 sections generally adhere sufficiently firmly to the slides 

 for all the ordinary methods of staining to be carried out 

 without detaching them ; thick sections, however, do not 

 adhere nearly so well. 



To prevent the risk of detachment, it is generally better 

 to cement the sections to the slides by the following 

 method., Equal parts of egg-white and glycerin are mixed 



