PARAFFIN SECTIONS 109 



for the knife or razor to have not only a keen edge, but 

 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 a 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 incu- 

 bator 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 



