VI] STAINING IMBEDDED SECTIONS 47 



c. If the sections require flattening, proceed as in 5, 6, 

 using dilute egg-albumin (2 c.c. filtered white of egg in 100 c.c. 

 water) instead of water. 



In either case when the paraffin has been dissolved from the 

 sections, leave them for 5 to 10 minutes in absolute alcohol, 

 then pass through alcohols and stain as in a. 



In this process the alcohol fixes the sections to the glass by 

 coagulating the film of egg-albumin. The drawback of the 

 process is that the egg- albumin is stained by most reagents. 



6. Staining sections still in paraffin. Sections cut in paraffin 

 may be stained, before the paraffin is removed, by floating them 

 on a staining agent. 



Sections of tissues which have been hardened in alcohol or 

 in mercuric chloride, stain with 1 p.c. aqueous solution of methy- 

 lene blue, or with Ehrlich-Biondi fluid and with other similar- 

 stains in ^ to | of an hour ; but they may be left for a day or 

 longer, and decolourized to the proper extent by floating in dilute 

 alcohol. Hsematoxylin stains in about a day. Eosin stains 

 rapidly and can be used after haematoxylin. Picro-carmine and 

 alcohol solutions of methylene blue stain so slowly by this 

 method that they are of little use. 



The most convenient method of treatment for most purposes 

 is to interpolate, after the sections are flattened, a stage of 

 staining in the ordinary process of mounting an already stained 

 section. The treatment then is as follows : 



a. The sections are flattened on warm water. 



b. They are taken up on a broad lifter and transferred to 

 the staining solution, on which they float. 



c. When stained, they are placed on water and gently moved 

 to remove excess of staining agent. 



d. They are taken up on a cover-slip (or slide) and the water 

 allowed to run from them. 



