Vil] SECTION CUTTING AND IMBEDDING 55 



along the point of junction of the paraffin mass and 

 the block, to melt it thoroughly and make a good 

 union. With the heated scalpel, heap up a little 

 paraffin about the base of the block. Leave for a 

 minute, then cool under the tap. 



6. Cutting sections, a. Take the tripod razor, 

 adjust as in 2, and cut sections in a similar manner, 



J O 



carrying the razor rapidly through the tissue, and 

 using the same portion of the razor. The successive 

 sections will stick together and form a ribbon. When 

 a ribbon of half-a-dozen sections has been made, place 

 it aside on a piece of paper, and cut a fresh ribbon. 

 The sections are mounted as in Lesson VI. 1, 3, or 4. 



b. The method given above, viz., of pouring paraffin with 

 the tissue into a watch-glass, serves very well for small objects ; 

 but as the surface of the watch-glass is curved, it is better when 

 objects more than half a centimetre in length are to be imbedded, 

 to use instead of the watch-glass, either a small card-board or 

 paper box, or two L-shaped imbedding frames. The latter are 

 made of brass or of lead, with sides about a centimetre high ; 

 they are placed on a glass slide so that the long limb of each is 

 in contact with the short limb of the other, they thus enclose a 

 space, the size of which can be varied according to the size of the 

 tissue ; into the space paraffin with the tissue is poured, and 

 the tissue is adjusted by a hot scalpel. 



7. The Rocking Microtome. Note the mechanism of the 

 microtome (Fig. 3). Turn up and down the large screw at the 

 end of the lever, and note the extent of the movement of the 

 anterior end of the lever which carries the paraffin. Turn 

 similarly the milled wheel at the base of the screw. Pull the 

 handle backwards and forwards, note that in pulling it forward, 

 a catch engages with the milled wheel and pushes it round, 

 i.e. pushes the paraffin on the lever towards the razor. Move 



