SECTION CUTTING. 1 29 



When about to begin cutting the sections,, the parafiSne 

 mass should be removed from the tray and trimmed to a con- 

 venient size, leaving more material behind the object than in 

 front of it. Slices should then be carefully taken from above 

 the object until it is reached and then even greater care should 

 be taken. In case a mass of tissue is being cut it should be 

 pared down until a good surface is reached, the slices taken 

 off being rejected. When an embryo is being cut every slice, 

 whether perfect or not, should be preserved. Always, when 

 cutting sections from parafifine embedding^, the up- 

 per surface of the razor should be flooded with 

 strong alcohol ; when soap is used water replaces 

 the alcohol and with glycerine jelly glycerine is 

 useful. The object of this is to float the object up 

 and prevent its sticking to the razor and thus be- 

 coming torn. It is convenient to have a shallow 

 tank before the worker filled with alcohol or water, 

 into which the razor with the section is dipped, the 

 section being floated off and the razor wetted for ^"^- 39 

 the next section at the same time. When a sufficient number 

 of sections have been cut from a paraffine embedding, the 

 embedded material may be sealed up by placing a drop or 

 two of melted paraffine on the cut end and the whole then 

 labelled and put aside for future sections. A specimen thus 

 embedded will keep for months without injury and may be 

 cut feom at any time. 



After cutting, the sections are to be freed from their em- 

 bedding material. In the case of paraffine this is accom- 

 plished by immersion in turpentine. AVhen soap, or gum, or 

 9 



