Reagents 29 



Camphor may be used instead of iodine to hasten the washing, but 

 it does not give any color reaction. 



Material should be imbedded as soon as possible, since it gets 

 brittle if allowed to remain in alcohol. 



Kinoplasmic structures do not stain well with gentian-violet, 

 but safranin and the haematoxylins stain almost as well as after 

 chromic-acid mixtures, and the carmines give their most brilliant 

 stains, as a result of the formation of mercuric carminate. 



The following formulae are merely suggestive: 



a) Corrosive Sublimate and Acetic Acid.- 



Corrosive sublimate 3 g. 



Glacial acetic acid 3 c.c. 



Alcohol (or water) 100 c.c. 



6) Corrosive Sublimate, Acetic Acid, and Picric Acid.- 



Corrosive sublimate 5 g. 



Glacial acetic acid. . 5 c.c. 



Picric acid, saturated solution in 50 per cent 

 alcohol 100 c.c. 



c) Corrosive Sublimate and Picric Acid (Jeffrey's solution) .- 



Corrosive sublimate, saturated solution in 30 

 per cent alcohol 3 parts 



Picric acid, saturated solution in 30 per cent 



alcohol 1 part 



It would be worth while to try other combinations. 



FORMALIN 



Formalin is an excellent preservative. It has been mentioned 

 already as an ingredient in several formulae. Commercial formalin 

 has a strength of 40 per cent. Throughout this book, a 2, 4, or 6 per 

 cent formalin is understood to mean 2, 4, or 6 c.c. of commercial 

 formalin to 98, 96, or 94 c.c. of water, alcohol, or any other ingredient. 

 Commercial formalin is sure to contain some formic acid. For most 

 purposes, it is neither necessary nor desirable to remove the acid. 

 For studying the origin of vacuoles, it is necessary to have neutral 

 formalin, which can be secured from commercial formalin by dis- 

 tillation. Place some sodium bicarbonate in a flask and distil by 



