348 ANATOMY OF THE DOMESTIC FOWL 



In placing specimen on the block be careful that the specimen lies 

 conveniently for cutting the sections in the right direction. As soon 

 as the surface has hardened a little, add a few drops of thick celloi- 

 din, and repeat until there is a good body of celloidin. Allow to 

 stand until the tissues are quite firmly fastened to the block, but 

 not long enough to permit shrinking. Then place in 80 per cent, 

 alcohol until the specimen is perfectly firm, 12 or more hours, be- 

 fore cutting. 



All tissues, cut sections, and mounted blocks are to be placed in 

 80 per cent, alcohol. As containers for this purpose shell vials will 

 be most handy. 



Cut the sections with the microtome as thin as possible, the 

 thinner the better. The following process of staining will make the 

 nucleus blue and the cytoplasm reddish. 



1. Float section in a tumbler of tap water. 



2. Place section on slide, and immerse in hematoxylon for five to ten minutes. 



3. Immerse in acid alcohol from two to five seconds. 



5. Place on slide, and immerse in eosin from one-half to three minutes. 



6. Wash thoroughly in alcohol. 



7. Clarify in oil of cloves, oil of cedar, or beechwood creosote, ten minutes. 



8. Mount in balsam. 



9. Label and study. 



Delafield's hematoxylon is prepared as follows: 



Hematoxylon crystals 4 grams 



Alcohol, 95 per cent 25 c.c. 



Saturated aqueous solution of ammonia alum. 400 c.c. 



Add the hematoxylon dissolved in the alcohol to the alum solu- 

 tion, and expose in an unstoppered bottle to the light and air for 

 three or four days. Filter and add: 



Glycerin 100 c.c. 



Alcohol, 95 per cent 100 c.c. 



Allow the solution to stand in the light until the color is sufficiently 

 dark; then filter, and keep in a tightly stoppered bottle. The 

 solution keeps well and is extremely powerful. So long as it is good 

 the solution has a purplish tinge. If time permits, it would be wise 

 to combine the alum, the hematoxylin, and the water, and to ripen 

 the solution for two or three weeks before adding the other ingredi- 

 ents, which have a tendency to prevent oxidation. 



