142 APPENDIX 



3. Aniline Blue. — This is a specific stain for callus depositions 

 on sieve-plates and is essential for the procedure outlined in 

 Exercise XI, Sections should be immersed for a short time in a 

 .1% aqueous solution, and then transferred, after gentle washing, 

 to a drop of water. The callus on the sieve-plates is stained blue. 

 Dr. A. S. Crafts has suggested to the writer the following 

 improvement: Place the sections in IKI, wash in water, stain in 

 aniline blue for about five minutes, then wash briefly again with 

 IKI and mount for study in tap water or glycerine. 



4. Neutral Red. — This vital stain is very useful in staining the 

 vacuome of plant cells and is recommended for use in Exercises 

 V, VI, and VII. Mount the sections directly in a .1% aqueous 

 solution. 



5. Sudan IV. — This reagent is specific for the cuticle, and for 

 cutinized and suberized cell walls. Place the sections in a drop 

 of alcoholic solution of Sudan IV (.5 g. in 100 cc. of 80% alcohol) 

 on a slide and warm gently over an alcohol flame. Add a cover- 

 glass and examine under the microscope. The cuticle, as well 

 as waxy materials present in walls are stained red. This reagent 

 is very desirable for use with Exercise V. 



