CHAPTER VIII. 



IMBEDDING METHODS PARAFFIN AND OTHER FUSION MASSES. 



128. Saturation with a Solvent.- The first stage of the 

 paraffin method consists in the saturation of the object with 

 some substance which is a solvent of paraffin. The process 

 is sometimes called a clearing process, since many of the 

 substances used for infiltration are also " clearing " agents. 



The process of saturation should be carefully performed 

 with 'well-dehydrated objects in the manner described in 

 106. 



Saturation liquids being liquids that are, on the one hand, . 

 miscible with alcohol, and on the other hand good solvents 

 of paraffin, are not quite as numerous as could be wished. 

 Amongst them may be mentioned essence of turpentine, clove 

 oil, bergamot oil, benzol, xylol, toluol, naphtha, oil of cedar- 

 wood, chloroform, and anilin oil. But they are by no means 

 all equally good, for few of them are as good solvents of 

 paraffin as is desirable. 



Turpentine penetrates well, and mixes readily with paraffin. 

 I do not, however, recommend it, because in my experience 

 it is of all others the clearing agent that is the most hurtful 

 to delicate structures. 



Clove oil penetrates well, and preserves delicate structures 

 well ; but it mixes very imperfectly with paraffin, and quickly 

 renders tissues brittle. 



Benzol has been recommended by BRASS (Zeit.f. wiss. Mik., 

 ii, 1885, p. 301). 



Toluol (or toluen) has been recommended by HOLL (Zool. 

 Am., 1885, p. 223). 



Naphtha has been recommended by WEBSTER (Journ.Anat.andPhysiol., 

 xxv, 1891, p. 278). For large specimens it has the advantage of being very 



