186 IMBEDDING METHODS. 



Methods." All that now remains is to get rid of the paraffin 

 and mount or stain as the case may be. The following 

 solvents of paraffin have been recommended for freeing sec- 

 tions from the paraffin with which they are infiltrated : Tur- 

 pentine, warm turpentine, a mixture of 4 parts of essence of 

 turpentine with 1 of kreasote, kreasote, a mixture of turpen- 

 tine and oil of cloves, benzin, toluol, xylol, thin solution of 

 Canada balsam in xylol (only applicable to very thin sections), 

 hot absolute alcohol, naphtha, or any other paraffin oil of low 

 boiling-point. Any of these may be used, but naphtha and 

 xylol are probably in most respects the best. Toluol also 

 works very well. 



If the slide be warmed to the melting-point of the paraffin,, 

 a few seconds will suffice to remove the paraffin if the slide 

 be plunged into a tube of naphtha or toluol. The sections 

 may be mounted direct from the naphtha, or the slide may 

 be brought into a tube of alcohol to remove the naphtha for 

 staining. 



284. Recapitulation of the Paraffin Method, as recommended 

 to be practised. Put into a small test-tube enough oil of 

 cedar to cover your object. On to the oil pour carefully the 

 same quantity of absolute alcohol. Take your (already de- 

 hydrated) object and put it carefully into the alcohol. Leave 

 it until it has sunk to the bottom of the cedar oil. Then put 

 it into paraffin kept at melting-point in a watch-glass. Let 

 the paraffin be of the very lowest melting-point that will give 

 sufficiently thin sections, and to this end work in a cool place, 

 so as not to be obliged to go above 45 C, if possible (see 

 also next section). After a time change the paraffin (i. e. put the 

 object into a fresh watch-glass with clean paraffin) once, or 

 twice if the object be at all large. As soon as the object is 

 thoroughly soaked with paraffin float the watch-glass on cold 

 water. When cool, cut out a block of paraffin containing the 

 object, and fix it with a heated needle on a cone of paraffin 

 already mounted on the object-carrier of the microtome. 

 Pare it square, and as close down to the object as possible on 

 all sides except the one turned towards the knife ; this had 

 better have a wall of a millimetre or two, or more, according 

 to the size of the object, left standing. Set the knife square. 

 Set the block square to the knife-edge. Cut sections in 



