284 STAINS AND STAINING. 



is found under Ehrlich's hsematoxylin, " After ripening it will keep 

 with a perfectly constant staining power for years. Sections are 

 stained in a few minutes. The stain is very appropriate for 

 staining in bulk, as overstaining does not occur." 



Many formulae have been written for haematoxylin solution, 

 but there are only three of them — Delafield's, Kleinenberg's, and 

 Ehrlich's — which are of general interest. In all three, alum is 

 present as one of the ingredients ; the idea being that the alu- 

 mina forms with the colouring matter an insoluble " lake," and 

 so acts as a mordant. 



Delafield's Hcematoxylin. 



In this there is nothing characteristic, except the large pro- 

 portion of alum to haematoxylin and the use of methylic alcohol 

 (wood spirit) in the place of rectified spirit. It is rendered in 

 some of the books as methylated spirit, which, however, possibly 

 answers just as well. 



As an instance of the same formula appearing under different 

 names, Lee, in his " Microtomist's Vade-Mecum," gives the fol- 

 lowing interesting history connected with Delafield^s solution : — 

 " It had long been in use in the Institute of Pathology at 

 Heidelberg, where it was communicated by Pfitzner to Flemming, 

 who published it and particularly recommended it. Flemming 

 then attributed the formula to Grenacher ; and, in consequence, 

 the stain went for years by the name of ' Grenacher's haema- 

 toxylin.' In 1885 matters were set right by Prudden explaining 

 that the stain was the invention of Delafield and publishing the 

 correct formula. This accounts for the same formula appearing in 

 different books as Delafield's and as Grenacher's." 



Kleinenber^s Hcematoxylin. 



Great differences exist in the wording of the formula given for 

 this solution. That given by Foster and Balfour in their Elements 

 of Embryology.^ published about twenty years ago, has been pub- 

 lished without comment into most of the text-books. 



A. — Make a saturated solution of crystallised calcium chloride 

 in 70 per cent, alcohol, and add alum to saturation. 



B. — Make a saturated solution of alum in 70 per cent, alcohol. 



C. — Add I part of ^ to 8 parts of B. 



