68 PRACTICAL HISTOLOGY. 



thereby in a saturated solution of oxalic acid, which extracts the 

 superfluous pigment. Mount sections in Farrant's solution or 

 balsam. (See Stomach.) 



B. Haematoxylin and Logwood. 



Hsematoxylin. This substance was introduced to the notice of 

 histologists by Bohmer. It is one of the most valuable nuclear 

 staining reagents we possess, and this is specially the case when its 

 violet-blue stain is set off by contrast with a ground stain of eosin, 

 picric acid, or other appropriate dye. 



1. Hsematoxylin (Bdhmer). Make a solution containing 



Hsematoxylin ..... i gram. 

 Absolute alcohol . . . . 100 cc. 



Make a second solution of 



Alum ...... 5 grams. 



Distilled water . . . . . 100 cc. 



Add drop by drop the first solution to a little of the second until 

 a deep- violet colour is obtained. The fluid is placed for fourteen 

 days in an open vessel, protected from dust, and exposed to the 

 light and air, when it becomes of a bluish tint. This fluid is said 

 to " ripen." Oxidation processes take place whereby the hsemato- 

 xylin is converted into hamatein. Filter. Add a fragment of 

 thymol to preserve it. It stains tissues in 5-15 minutes. 



It is sufficient to make a saturated solution of the crystals of 

 haernatoxylin in a small quantity of absolute alcohol. Add a few 

 drops to a i per cent, solution of alum, which yields a light violet- 

 coloured fluid. Expose the fluid to light and air, when it becomes 

 blue. It is well to prepare this fluid several weeks beforehand to 

 enable it to " ripen." 



The ordinary manipulative procedure for hsematoxylin staining is 

 as follows : 



(1.) Stain the section (2-10 minutes). 



(2.) Wash in distilled water. 



(3.) Allow section to remain 12-24 hours in distilled water. 



(4.) Remove water with alcohol, add ethereal oil, balsam. 



Bohmer's hsematoxylin is well adapted for staining sections. It 

 is best adapted for tissues hardened in sublimate, alcohol, picric or 

 nitric acid, and not so good for those from chromium salts or osmic 

 acid. Sections to be stained with it before being placed in the dye 

 are better to be placed first in water or in i per cent, alum solution. 

 If taken direct from alcohol they may contain a deposit after being 

 stained. After staining, the sections are thoroughly washed in 

 ordinary water. Haematoxylin stains the chromatin of the nuclei 



