124 H^MATEIN AND OTHER OEGANIC STAINS. 



Kanvier re-dissolves this precipitate in 1 per cent, solution of alum, and 

 employs the solution for staining sections of epidermis that have been 

 hardened in bichromate of potash. The sections should remain twenty-four 

 hours in the liquid. Nuclei are then found stained light violet, the granules 

 of eleidin dark violet. CONTEJEAN (Bull. Soc. Philomath. Paris, 8, 3 

 1891, p. 117) has given a receipt for preparing this product by precipitating 

 solution of Bohmer with baryta water. (Cf. Mayer, in Mitth. a. d. Zool. 

 Stat. zu Neapel, 10, 3, 1892, p. 500.) The stain is a very fine one ; but 

 critically examined, these methods appear to be only roundabout methods 

 of getting a solution of htematein in alum. 



188. Ehrlich's Acid Haematoxylin (Zeit. f. wiss. Mik., 1886, 

 p. 150). The ordinary (alum) haematoxylin staining solutions 

 easily decompose, giving rise to a blue precipitate which is 

 formed by the splitting up of the alum into free sulphuric acid 

 and a basic, lake-forming compound of alumina. By adding 

 to a solution an appropriate acid this decomposition may be 

 prevented. The end may be attained by acetic acid. Take 



Water 100 c.c. 



Absolute alcohol . . . 100 



Glycerin 100 



Glacial acetic acid . . . 10 

 Haematoxylin .... 2 grammes. 

 Alum in excess. 



Let the mixture ripen in the light (with occasional admission 

 of air) until it acquires a dark red colour. It will then keep, 

 with a perfectly constant staining power, for years, if kept in 

 a well-stoppered bottle. Sections are stained in a few minutes. 

 The stain is also very appropriate for staining in bulk, as 

 over-staining does not occur. 



In order to get a blue stain with this acid solution, the 

 stained objects should be treated as directed supra, 178, 

 but common tap-water may suffice. 



For double-staining, either acid colouring matters (" Farb- 

 sauren"), such as eosin, or "basic colouring matters" ("Farb- 

 basen"), may be added to the solution. 



This is one of the most important of the alum haema- 

 toxylins. 



188a. Ammoniated Haematoxylin (SQUIEE, Methods and For- 

 mul&, &c., p. 24). " Haernatoxylin, 2 grms. ; ammonium 

 carbonate, - 4 grm. ; proof spirit, 40 c.c. Dissolve the am- 

 monium carbonate and the haematoxylin in the proof spirit 



