CHOICE OF A STAIN. 57 



orange method ( 258), or gentian andeosin (Chap. XIII) for 

 a double stain. 



For staining in toto Grenacher's alcoholic borax-carmine 

 ( 169), or Mayer's carmalum ( 151), unless the object 

 be so impermeable as to require a more highly alcoho- 

 lised stain, in which case take Mayer's para-carmine 

 ( 168), or for chromic acid objects Mayer's haemacalcium 

 ( 182). 



For fresh dissociated tissues or small entire objects, methyl 

 green, if it is not important to have permanent preparations ; 

 if it is, take alum-carmine. 



Picric acid may be used for double staining after carmine 

 or hsematoxylin. 



Many others of the numerous stains discussed in the follow- 

 ing chapters render most valuable services, and will be 

 found recommended in the special paragraphs as occasion 

 dictates. 



I would add one word of advice to the beginner : never use 

 a double stain where a single one will do. To do so is too 

 often to go farther and fare worse. 



And a word of caution to beginners and others : 



You are not likely to succeed in staining, especially in the 

 beautiful processes of staining with coal-tar colours, unless you 

 see to it that you are working with chemicals of the proper 

 quality. You cannot ensure this by going to a generally 

 trustworthy house for chemical products at all events, not 

 in the case of coal-tar colours. It is not sufficient that these 

 should be what they are commercially described to be ; they 

 may be pure, and yet not give good stains. They must (in 

 the case of anilins, at all events) be the identical products 

 used in their work by the authors who have described and 

 recommended them (see[the note on the numerous safranins in 

 the market, 101). I therefore feel constrained to advise 

 everybody to get his reagents at all events his anilins 

 from the well-known chemists Grubler and Miinder. Griibler 

 has all the tried reagents in stock, and supplies only such as 

 have been found by experiment with tissues to furnish the 

 desired stain. He also makes up fixing and staining solu- 

 tions, injection and imbedding masses, &c., according to the 

 classical formulae, and sends them out neatly packed and ready 

 for use. From experience I can most highly recommend these 



