500 HISTOLOGY 



elements only. Certain stains may be applied to the tissue before it is 

 imbedded and sectioned. They are seldom used except in the prepara- 

 tion of embryos. 



GENERAL STAINS. 



THE STAINING OF SECTIONS. 



Haematoxylin and Eosin. Haematoxylin is a basic dye obtained from 

 logwood, which stains nuclear structures blue. Eosin is an acid anilin 

 dye which stains cytoplasm red. (It is recommended that all anilin 

 dyes used in histological work be those prepared by Griibler in Germany.) 



There are many formulae for the preparation of haematoxylin solutions, 

 of which the two following are especially useful. 



Alum haematoxylin. 



Haematoxylin crystals i gm. 



Saturated aqueous solution of ammonia alum 100 c.c. 



Water 300 c.c. 



Dissolve the haematoxylin in a little water with the aid of heat, and 

 add to the remainder of the solution. Put the mixture in a bottle and 

 add a small lump of camphor or thymol to prevent the growth of mould. 

 Stopper the bottle with a loose plug of cotton and set in the light for about 

 10 days to ripen. It changes to a deep blue color during this process of 

 oxidation, after which it is ready for use and is kept tightly stoppered. 

 It deteriorates and must be renewed after a few months. The solution 

 may be ripened immediately by the addition of 2 c.c. of hydrogen peroxide 

 solution, neutralized by a crystal of sodium chloride. 



For use after Zenker fixation, the water in the above formula may be 

 omitted. 



Delafield's Haematoxylin. 



Hsematoxylin crystals 4 gm. 



Alcohol, 95 per cent 25 c.c. 



Sat. aq. sol. of ammonia alum 400 c.c. 



The haematoxylin is dissolved in the alcohol and added to the alum 

 solution. This is exposed to the light in an open vessel to ripen for about 

 4 days and then is filtered. To the filtrate is added: 



Methyl alcohol (or 95%) 100 c.c. 



Glycerin 100 c.c. 



This mixture is exposed to the light in a cotton-plugged bottle for 

 about a week, after which it is again filtered and tightly stoppered. The 

 solution keeps for a considerable time. It may be used in this strength, 

 but preferably it is diluted with one or two volumes of water. 



Eosin is sold in two forms, one soluble in water, the other in alcohol. 

 In connection with haematoxylin, a T V to i per cent, aqueous solu- 



