778 Methods of Microscopical Research [October, 



(3) Borax Carmine} — a. An aqueous solution of borax (4 per 

 cent.) and carmine, heated till the carmine is dissolved. 



b. Solution a mixed with 70 per cent, alcohol in equal parts, 

 left standing twenty-four hours and filtered. 



This fluid may be used for coloring objects in toto. After 

 staining, the objects are to be washed in 35 per cent, alcohol, to 

 which a little hydrochloric acid has been added (4-6 drops to 

 100 ccm.), and allowed to remain here until the color has been 

 sufficiently removed. They are next passed through successively 

 higher grades of alcohol for hardening. 



(4) Alcohol Carmine. — A teaspoonful of carmine dissolved, by 

 heating about ten minutes, in 50 ccm. of 60-80 per cent, alcohol, 

 to which 3-4 drops of hydrochloric acid have been added, then 

 filtered. 



Objects colored in this fluid should not be washed in water, 

 but in alcohol of a grade corresponding to that of the solution. 



For diluting alcoholic solutions of carmine, alcohol of the 

 same strength must always be used. 



6. Aniline Dyes. — As a rule, aniline colors and the many others 

 obtained recently from tar by chemical processes, can not be used 

 for staining objects in toto, and are therefore not much employed 

 in the Zoological Station. In very small objects and sections 

 already cut, very excellent results can be obtained by the meth- 

 ods developed by Bottcher, 2 Hermann, 3 Flemming 4 and others ; 

 for here diffuse staining may generally be avoided by first over- 

 staining and then withdrawing the color to any desired extent by 

 means of alcohol. But to obtain satisfactory results, the sections 

 must be thin enough to allow uniformity of action both to the 

 coloring and the decoloring agent. It is evident that the process 

 cannot be similarly controlled in larger objects, particularly where a 

 dye is used, which, like most of those under consideration, is quickly 

 extracted by alcohol, for in this case the color would be removed 

 from the superficial layers more rapidly than from the deeper 



