Fixing Sohitiojis and tlieir Uses 19 



Good for invertebrate material. Does not give a oood histological pic- 

 ture; cytoplasm is badly shrunken. W^ish in 50% alcohol. Post-treat 

 for mercuric chloride. Good for beginners, easy to work with. 



Johnson's fixative {Gatenby, 1950): 12 hours. 



potassium dichromate, 2.5% aqueous (2.5 gm./ 



100 ml. water) 70.0 ml. 



osmic acid, 2% aqueous (2 gm./lOO ml. water) 10.0 ml. 



platinum chloride, 1% aqueous (1 gm./lOO ml. 



water) 15.0 ml. 



glacial acetic acid 5.0 ml. 



Contracts spongy protoplasm less than Flemming's. Wash in water. 



Hermann's modification: 12-16 hours. 



platinum chloride, 1% aqueous (1 gm./lOO ml. 



water) 15.0 ml. 



glacial acetic acid 1.0 ml. 



osmic acid, 2% aqueous (2 gm./lOO ml. water) 2.0-4.0 ml. 



Better protoplasm than with chromic mixtures. Good nuclear stain- 

 ing, but not of plasma. Some shrinkage of chromatin. Without acetic 

 it is sood for mitochondria. 



o^ 



kolmer's fixative: 24 hours. 



potassium dichromate, 5% aqueous (5 gm./lOO 



ml. water) 20.0 ml. 



10% formalin 20.0 ml. 



glacial acetic acid 5.0 ml 



trichloracetic acid, 50% aqueous (50 gm./IOO ml. 



water) 5.0 ml. 



uranyl acetate, 10% aqueous (10 gm./IOO ml. 



water) 5.0 ml. 



Good for entire eye [Wall, 1938) or nerve tissue, due to presence of 

 uranium salts. Wash in running water. 



LAVDOWSKY FLUID {Swigart et al., I960): 12-24 hours. 



distilled water 80.0 ml. 



95% ethyl alcohol 10.0 ml. 



chromic acid, 2% aqueous (2 gm./IOO ml. water) 10.0 ml. 



glacial acetic acid 0.5 ml. 



Good for glycogen. Transfer to 80% alcohol. 



