PREFACE 



Stain Technique is designed to provide concise instruction in 

 the correct usage of biological stains by introducing the chemistry 

 of color precipitates, the arrangement of stains into a few classes 

 depending on their manner of application, and the outline for stain- 

 ing with combinations of two, three, or four dyes. The results of 

 numerous tests with each dye indicate the action of acids, alkalies, 

 and salts; the composition of effective stains; the influence of re- 

 agents on the fastness of color; the affinity for tissues of algae, 

 fungi, mosses, vascular plants, invertebrate and vertebrate ani- 

 mals; and the combination of stains which provide contrasting 

 colors. Because most of the experimental products are of nega- 

 tive value, many of the dyes merit only a brief statement. A few 

 superior and distinctive coal-tar dyes are worthy of admission into 

 standard methods. Hence, the fundamental plan of this textbook 

 is extended to include those phases which assist the student in a 

 practical application of stain technique. 



