Killing, Fixing, and Storing Plant Tissues 21 



by weight, and 0.5' i acetic acid by \olunie. Table -5.1 gives the 

 proportions of stock sohitions used to make 100 cc. oi mixtures in 

 this category. 



A variant of the Nawaschin formula, Craf 0.20-1.0-10.0, contains 

 0.2% chromic acid, 1.0% acetic acid, and lO.O^o commercial form- 

 aldehyde solution. A \ariant of the Allen-Bouin formula is designated 

 A-B 0.20-4.0-10.0-25.0, containing in addition to the ingredients of 

 Craf, a saturated acjueous solution of picric acid, 25.0% by volume. 



The foregoing system of terminology is accurate, descriptive, and 

 convenient and has been used successfully by beginners and advanced 

 workers. 



