152 H MM AT BIN 



Hance {Science, 77, 1933, p. 287) recommends the addition of 

 a little sodium bicarbonate to freshly prepared haematoxylin 

 solution, noting that the staining and keeping properties of the 

 solution are greatly improved. 



279. Haematein is found in commerce as a brown powder, 

 entirely, 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. (See also previous editions.) 



280. Iron Haematoxylin, Generalities.* This method is due to 

 Benda {Verh. Phys. Ges., 1885—1886, Nos. 12, 13, 14; Arch. 

 Anat. Phys., 1886, p. 562 ; third ed. of this work, p. 365). 



The method was independently worked out about the same 

 time by M. Heidenhain. The method is almost universally 

 practised in the form given by Heidenhain, not on account of 

 any essential difference between the two, for there is none, but 

 chiefly because Heidenhain has given more precise instructions 

 concerning the process. 



After carefully comparing Heidenhain's process with Benda's 

 later process (next §), we find that the two give an absolutely 

 identical stain ; that is to say, that if you mordant in Benda's 

 liquor ferri (next §), and differentiate in the same, you will get 

 exactly the same effect as by mordanting in ferric alum and 

 differentiating in the same. But you may vary the results 

 somewhat by varying the differentiation. Benda has pointed 

 out (Verb. Anat. Ges., xv, 1901, p. 156) that you may differentiate 

 either by an agent which simply dissolves the lake — -such as 

 acetic or hydrochloric acid ; or by an oxidising agent, such as 

 chromic acid, or the liquor ferri or the ferric alum. The former, 

 he thinks, are the best for the demonstration of nuclear structures, 

 the latter for cytoplasmic structures. For these he greatly 

 recommends Weigert's borax-ferricyanide mixture, as being the 

 easiest and safest to employ. 



We find that differentiation in the iron salt (§281 or §282) is 

 sufficient for almost all purposes. Acetic acid of 30 per cent, 

 acts much too quickly to be safe, and causes swelling of the 

 tissues. 



Van Gieson's picro-saurefuchsin has been recommended as 

 a differentiation fluid by Benda {Deutsch. med. Wochenschr., 

 1898, No. 30). We find it gives very delicate differentiations, 

 but acts very slowly, requiring nearly as many hours as the 

 iron alum solutions does minutes. The addition of the saure- 

 fuchsin to the picric acid is, we find, not necessary, and may 

 prove an injurious complication. 



In these processes haematoxylin is generally used for the stain, 

 not hwmatein, the iron salt oxidising it into haematein, or into a 



* See also §§ 627, 693, 1365. 



