134 



dehydrated by bathing with alcohol of successive strengtns 

 up to 96^. 



The following stains we use commonly and find excellent 

 for most work : — 



FOR STAINING SECTIONS. 



Mayer's acidulated carmine (Lee's Vade-Mecum, p. 174). — 

 Carminic acid, 4 grams, distilled water, 15 c.c, hydrochloric 

 acid, 30 drops. Boil till the carmine is dissolved, and after 

 cooling add 95 c.c. of alcohol of 85^ strength (or for stain- 

 ing /// toto use alcohol of 95^ strength), and filter the fluid. 

 After filtering, the now acid solution should be made neutral 

 by slowly adding drops of ammonia until neutralization is 

 effected. This gives a beautiful, deeply-red-colored, and 

 quickly acting stain. Leave the slide in the stain from five 

 to fifteen or twenty minutes. Remove to 70^ alcohol for 

 washing and then to 96^ alcohol. It will be noted that, in 

 addition to the sections, the thin coating of albumen fixative 

 on the slide has been slightly stained. This can be removed 

 by passing the slide quickly through 96^ alcohol containing 

 a very little (i to 1000) hydrochloric acid. This bath of 

 acidulated alcohol also " differentiates " the stain, i.e., takes 

 out some of the stain from the cytoplasm of the cells, leav- 

 ing the cytoplasm much more faintly stained than the nuclei. 

 From the acidulated alcohol the slide should be removed to 

 pure 96^ alcohol. (For further manipulation see Clearing 

 and Mounting, /(?j/'^<7.) 



Gre?iacher's alcoholic borax-carmine (Lee, p. 172). — Make a 

 concentrated solution of carmine in borax solution (2 to 3 

 per cent, carmine to 4 per cent, borax) by boiling for half an 

 hour or more ; dilute it with about an equal volume of 70^ 

 alcohol, allow it to stand 24 hours and filter. Add to this 

 solution an equal amount of 70;^ alcohol ; allow the mixture 



