HARDENING 1 15 



FREEZING METHOD. 



1. Fixation. Place the pieces of tissue in a wide- 

 mouthed glass bottle and fill with absolute alcohol. Al- 

 low the tissues to remain therein for twenty-four hours. 



2. Hardening. Remove the alcohol (no longer abso- 

 lute, as it has taken up water from the tissues) from 



FIG. 71. Washing tissues. 



the bottle and replace it with fresh absolute alcohol. 

 Allow the tissues to remain therein for twenty-four 

 hours. 



NOTE. If not needed for cutting immediately, the hardened 

 tissues can be stored in 75 per cent, alcohol. 



3 . Remove the alcohol from the tissues by soaking in 

 water from one to two hours. Remove the stopper 

 from the bottle; rest a glass funnel in the open mouth 



