HARDENIKG AND FIXING REAGhXTS. 7 



(v.a) KLEIN'S FLUID. 



Chromic Acid solution (10 p. c.) 1 cc. ; mix with. Water 

 60 cc. ; then add 90 p. c. Alcohol, 30 cc. 



The Alcohol is added to increase the penetration of the 

 Chromic Acid. This solution should be made fresh as re- 

 quired and kept from the light, as the Chromic Acid is 

 rapidly reduced by the Spirit. 



Suitable for all tissues, but more particularly the nervous 

 system. The fluid must be changed every day for the first 

 three days, and then every third day. The hardening is com- 

 plete in about a week to a fortnight. 



In all cases except the nervous system, the tissue after 

 hardening must be well washed in Water, and preserved in 

 70 p. c. Alcohol. 



The nervous system should be transferred direct from 

 Klein's Fluid to the Alcohol. 



(v.J) RABL'S FLUID. 



Chromic Acid solution (10 per cent.), 7 cc. ; Water, 200 cc. ; 

 Formic Acid (sp. gr. 1*2), 5 drops. 



Fresh tissues in small pieces are placed in it from 12 to 24 

 hours; they are then washed in Water and hardened in 

 Alcohol of gradually increasing strength. 



This solution is especially useful for demonstrating cell 

 division (mitosis) and nuclei. 



The following are used more particularly as fixing agents. 



(vi.) CORROSIVE SUBLIMATE. 



5 p. c. aqueous solution. 



This is a capital fixing agent, and acts quickly. 



