TECHNIQUE. 45 



The mixture is made by adding one part of abso- 

 lute alcohol to 2 parts of the saturated solution of 

 mercuric chloride and it should be used warm, the 

 preparations being immersed for from 2 to 5 minutes. 

 They are then washed in 50 per cent, alcohol, and 

 70 per cent, alcohol, and then placed in 70 per cent, 

 alcohol to which enough tincture of iodine has been 

 added to give a port wine color. They are allowed 

 to remain in this mixture until they turn a pale yel- 

 low, when they are rinsed in 70 per cent, alcohol, 

 and hardened in 80 per cent, alcohol for at least a 

 quarter of an hour. 



Acetic Acid Solution of Picric Acid and Mer- 

 curial Sublimate. This mixture consists of equal 

 parts of a saturated solution of mercuric chloride 

 prepared as above ; picric acid, 1 per cent, in distilled 

 water; and a J/ to 1 per cent, solution of glacial 

 acetic acid. This method is most useful in fixing 

 portions of tissue containing amoeba?. The tissue 

 should be left in the mixture over night and then 

 washed in 50 per cent, and 70 per cent, alcohol. 



Sublimate Acetic Acid Mixture. This mixture 

 consists of 95 parts of a saturated solution of sub- 

 limate of mercury in distilled water and 5 parts of 

 glacial acetic acid. The cover glasses containing the 

 material to be examined are placed directly in this 

 mixture while wet or after a preliminary fixation with 

 osmic acid vapor. 



