62 PRACTICAL HISTOLOGY [VIII 



e. Use 4 p.c. formaldehyde in alcohol about 75 p.c. (1 part 

 formol and 9 parts 80 p.c. alcohol) for the mercuric fluid of d. 

 (This may be used for any tissue, but the sections stain diffusely, 

 unless well washed.) 



If, in methods (6) and (c), the tissue can be left longer in the 

 fixing agent or in the absolute alcohol, this should be done. 



The tissue may be passed back through the alcohols, to water, 

 and to gum, then cut frozen and stained ; or they may be put 

 for 10 minutes in cedar- wood oil or xylol, imbedded, the sections 

 fixed to a cover-slip and stained. 



2. Staining in bulk with hcematoxylin. Place a small piece 

 of hardened tissue in Delafield's haematoxylin diluted with about 

 three volumes of distilled water (first placing it, if necessary, in 

 30 p.c. alcohol for a quarter-of-an-hour). Leave for two days 

 unless the piece of tissue is thin, in which case one day may be 

 sufficient. Wash with distilled water, leave half-a-day in tap 

 water, place for half-an-hour, or longer, in each of the several 

 grades of alcohols. Put in cedar- wood oil in the warm for \ to 

 | an hour (cp. Less. vu. 5) ; and in melted paraffin for an 

 hour. 



The stay in the several fluids should be longer, the larger the 

 piece of tissue. It is advisable but not necessary to use absolute 

 alcohol. 



3. Staining in bulk with hcematoxylin and eosin. Stain with 

 hsematoxylin as in 2, but use acid-haematoxylin instead of 

 Delafield's, and leave the tissue in it for three days. After the 

 tissue has been treated with 75 p.c. alcohol, put it in 95 p.c. 

 alcohol containing ! p.c. eosin for a day ; wash with 95 p.c. of 

 absolute alcohol (10 to 15 minutes) ; treat with cedar- wood oil 

 and paraffin as in 2. 



NOTES. 



In staining in bulk as given above the outer parts of the 

 tissue are usually stained much deeper than the inner. This 

 may to a certain extent be avoided by further diluting the stain, 

 and leaving the tissue longer in it. 



