ADDITIONS. 389 



given on p. 366, 4. The paraffin is sliced away 

 until the surface is very nearly reached, then the 

 paraffin at the sides of the tissues is sliced away in 

 such a manner that the surface to be cut is rect- 

 angular. The shaped end of the paraffin block is 

 dipped for a moment in melted soft paraffin, i.e. 

 paraffin melting at about 40 C. The block is fixed 

 in a microtome, and arranged so that the edge which 

 meets the razor is parallel to the edge of the razor, 

 the soft paraffin may be cut away from the two 

 sides of the block which are at right angles to the 

 razor edge. The soft paraffin causes each section as 

 it is cut to stick to the preceding one, and thus a 

 ribbon of sections is obtained. Of the less expensive 

 forms of microtome adapted for cutting ribbons of 

 sections the most convenient is the Rocking Micro- 

 tome of the Cambridge Scientific Instrument Com- 

 pany. In this a short tube is filled with hard 

 paraffin, and the base of the block of paraffin con- 

 taining the tissue to be cut is sliced away within a 

 few millimetres of the tissue, this is held down on 

 the paraffin mass of the microtome tube and a hot 

 knife passed between the two surfaces and around 

 the junction of the block with the paraffin mass. 

 Thus the tissue to be cut is firmly fixed when the 

 paraffin solidifies. It is best to do this before coat- 

 ing with soft paraffin. 



Mounting. Take a thin solution of white shellac in 

 kreosote and paint a thin film of it over a clean 

 dry glass slide. On this place the section or sec- 

 tions it is desired to mount, press each gently with 

 a camel hair brush to make it lie flat. Place the 

 slide in a warm chamber until the paraffin is melted; 



