FIXING AND HARDENING AGENTS. 65 



containing tincture of iodine). I consider this a very fine 

 reagent. 



OHLMACHER (Journ. Exper. Medicine, ii, 6, 1897, p. 671) has arrived 

 independently at a sublimate modification of Cavnoy's original chloroform 

 liquid. He takes 



Absolute alcohol . . . . .80 parts. 

 Chloroform . . . . . 15 ,, 



Glacial acetic acid . . . . 5 ,, 

 Sublimate to saturation (about 20 per cent.). 



" Ordinary pieces " of tissue are sufficiently fixed in fifteen to thirty 

 minutes. Entire human cerebral hemispheres, subdivided by Meynert's 

 section, take eighteen to twenty-four hours. Wash out in iodine alcohol 

 ( 66). Although this liquid is historically a modified acetic-alcohol, yet 

 in view of the relatively small amount of acid in it, it should rather be 

 classed as an alcoholic sublimate solution, 69. 



85. Formic Acid may be used dilute in the same way as acetic acid 

 (supra. 82). It is possible that it might also take the place of acetic 

 acid in the concentrated form, but I ain not aware of any experiments in 

 this direction. 



86. Chloride and Acetate of Copper (Ripart et Petit's 

 Liquid, CAKNOY, La Bioloyie Cellulaire, p. 94). 



Camphor water (not saturated) . 75 grammes. 

 Distilled water . . . . 75 ,, 



Crystallised acetic acid . . .1 gramme. 



Acetate of copper . . . 0*30 ,, 



Chloride of copper . . . 0*39 ,, 



This is a very moderate and delicate fixative. I consider 

 that it has not sufficient hardening' power for objects that 

 are intended to be dehydrated and mounted in balsam, but 

 is frequently excellent and sometimes indispensable for 

 objects that are to be studied in as fresh a state as possible 

 in aqueous media. Objects fixed in it stain instantaneously 

 and perfectly with methyl green. Osmic acid may be added 

 to the liquid to increase the fixing action. For cytological 

 researches this is a most invaluable medium. 



87. Acetate of Uranium. (SCHEXK, Mittli. a. d. Embryol. Inst. Wien, 

 1882, p. 95 ; cf. GriLsox, La Cellule, i, 1885, p. 141). This reagent is very 

 similar in its properties to picric acid. It has a mild fixing action, and a 

 high degree of penetration, which may make it useful for Arthropoda. It 

 may be combined with methyl green, which it does not precipitate. 



For Acetate of Lead see " Neurological Methods," Hardening. 



5 



