APP.] IMBEDDING. 433 



to imbed soak it in turpentine' until it is com- 

 pletely saturated : and transfer it thence with as 

 little turpentine as possible to a dish of melted 

 paraffin. 



In cases of very delicate tissues, it is better to use 

 chloroform instead of turpentine. The chloroform 

 should be carefully added by means of a pipette to the 

 absolute alcohol in -which the tissue is placed. The 

 chloroform sinks to the bottom of the bottle or tube 

 and the embryo, which at first lies at the junction of the 

 two hquids, gradually sinks into the chloroform. When 

 this is accomplished, remove all the absolute with a 

 pipette and add pieces of solid paraffin to the chloroform. 

 Gently warm this on a water bath till all the chloroform 

 " is driven off ; then imbed in the usual way. 



Care must be taken that no more heat is 

 used than is necessary to melt the paraffin ; for 

 this purpose the paraffin should be warmed over 

 a water bath the temperature of which is kept 

 constant (from 50 to GO^C. but not more than 



eo^c). 



A paraffin melting at 44PC. is of the proper consistency 

 for cutting when the temperature of the room is 15*C. 

 (600F). 



With care a porcelain evaporating dish and 

 a gas flame may be made to answer, but the 

 student is advised not to imbed without a 

 water bath. 



The embryo may be left in the paraffin two, 

 three or more hours, after which it is imbedded 

 by placing it along witb the melted paraffin in 

 either a box made by bending up the sides and 

 folding in the corners of a j^iece of stiff paper, 

 or what is better, a box formed by two L-shaped 



^ If the alcohol is not quite absolute kreasote should be used 

 instead of turpentine. 



F. & B. 28 



