47 



is taken out of the cedar-wood oil and the excess wiped 

 off in order to prevent the oil softening the paraffin. 



2. Place in a dish of melted paraffin for half 

 an hour, more or less according to the size of the tissue. 

 (If on removing and allowing the block to cool a cut 

 made with a razor through the tissue looks quite 

 uniform, it is a sign that the paraffin has penetrated 

 properly). 



3. Arrange two brass blocks (L pieces) on an 

 ordinary slide so as to form a trough of the required 

 dimensions. Melt some paraffin in a dish and fill up 

 the trough to the top. Now transfer the tissue with 

 a warmed forceps to the trough and arrange as 

 required. (As soon as the surface becomes opaque 

 and semi-solid, the position of the object, if necessary, 

 may be marked by scratching with a needle on the 

 paraffin.) 



4. When the surface is solid, but not before, 

 cool under a tap of water. 



5. Trim the block by cutting away successive 

 slices. Take care that the sides are parallel. (Block 

 trimmers are very useful where continuous series of 

 sections are to be cut.) 



6. Put some paraffin on the block holder, warm 

 in flame and now press on the paraffin block firmly 

 until it adheres. Melt bits of paraffin around the base 

 with a hot knife to give it further support. 



Treatment of Sections. I. Place a trace (pin-head 

 size) of egg albumen and glycerine on a slide and rub 

 it carefully over with the finger (free from grease). 



2. Just cover the slide with water from a pipette. 



3. Lift a section (or ribbon if required) from the 

 microtome with a strip of note paper. Avoid touching 

 the knife. Now with the needle carefully draw the 

 ribbon on to the water and repeat the operation until 



