154 CHAPTEII xnr. 



become quite dark. It has then become to a great extent 

 oxidised into ha3inatein, and the staining solutions made up 

 from it will be at once fairly ripe. 



Haematein (or haematoxylin) affords a stronger stain than 

 carmine, and gives better results with tissues fixed in osmic 

 or chromic mixtures". The alum solutions are indicated for 

 staining in bulk, iron haematoxylin for sections. 



238. Haematoxylin is found in commerce in the form of 

 crystals,, either colourless or browned by oxidation,, easily 

 soluble in either water, glycerin, or alcohol. 



Haematein is found in commerce as a brown powder, en- 

 tirely, though with difficulty, soluble in distilled water and 

 in alcohol, giving a yellowish-brown solution, which remains 

 clear on addition of acetic acid. Alkalies dissolve it with a 

 blue-violet tint. 



MAYER (Zeit. wise. Mik., xx, 1903, p. 409) prepares it as follows: 

 1 grin, of hseniatoxyliii is dissolved by boiling in not more than 10 c.c. 

 of distilled water, and to the solution is added a hot solution of 0'2 grin. 

 of iodate of sodium in about 2 c.c. of water. Mix well and cool by 

 placing the recipient in cold water. After a couple of hours bring the 

 mixture on to a filter, wash thereon with cold water to remove the 

 excess of iodide of sodium that has formed, then dry the residue. 



There is also found in commerce an ammonia-compound 

 of hgematein haematein-Ammonialc, also known as Hsema- 

 teinum crystallisatum ; this may be obtained in a sufficiently 

 pure state from GRUBLER & HOLLBORN. 



This is somewhat more easily soluble in both water and 

 alcohol than hsematein is, and does quite as well for staining 

 purposes. It can be made as follows : 



239. Haemateate of Ammonia (MAYER, Mittli. Zool. Stut. 

 \. 1891, p. 172). Dissolve 1 grm. of liseniatoxylin with the aid of heat 

 in 20 c.c. of distilled water, filter if necessary, add 1 c.c. of caustic 

 ammonia (of 0'875 sp. gr.), and bring the liquid into a capsule of such 

 dimensions that its bottom be covered to a depth of not more than half 

 a centimetre. Let the liquid evaporate at the ordinary temperature 

 and be protected from dust. The dry product will consist of hsemateate 

 of ammonia, about equal in weight to the hsematoxylin taken in the 

 first instance. The evaporation should not be hastened by heat, as this 

 may give rise to the formation of substances that are insoluble in 

 alcohol. The preparation should not be toadied, until it is dry, with 

 any other instruments than such as are made of glass, porcelain, or 



