THE CELLOIDIN METHOD 135 



The following schedules, beginning with the celloidin sections in 70 

 per cent alcohol, will give the student a start in the staining: 



Delafield's haematoxylin and eosin. — 



1. Seventy per cent alcohol, 2-5 minutes. 



2. Delafield's haematoxylin, 5-30 minutes. 



3. Wash in water, 5 minutes. 



4. Acid alcohol (1 c.c. hydrochloric acid+100 c.c. of 70 per cent alcohol) 

 until the stain is extracted from the celloidin, or at least until only a 

 faint pinkish color remains. 



5. Wash in 70 per cent alcohol (not acid) until the purple color returns. 



6. Stain in eosin (preferably a 1 per cent solution in 70 per cent alcohol), 

 2-5 minutes. 



7. Dehydrate in 95 per cent alcohol, 2-5 minutes. Do not use absolute 

 alcohol unless you wish to dissolve the celloidin, which is not necessary 

 with this staining. 



8. Clear in Eycleshymer's clearing fluid, usually 1-2 minutes, but some- 

 times 5-10 minutes. 



9. Mount in balsam. 



Safranin and Delafield's haematoxylin. — 



1. Seventy per cent alcohol, 2-5 minutes. 



2. Safranin (alcohohc), 6-24 hours. 



3. Acid alcohol (a few drops of hydrochloric acid in 70 per cent alcohol) 

 until the safranin is removed from the cellulose walls. 



4. Wash in 50 per cent alcohol, 5-10 minutes to remove the acid. 



5. Delafield's haematoxylin, 2-5 minutes. 



6. Wash in water, 5 minutes. 



7. Acid alcohol, a few seconds. 



8. Dehydrate in 95 per cent alcohol, 2-5 minutes, then in absolute alcohol, 

 2-5 minutes, which will partially dissolve the celloidin. 



9. Clear in clove oil, which will complete the removal of the celloidin. 

 10. Be sure that the sections are free from fragments of celloidin and then 



mount in balsam. 



Stains which can be used with celloidin are limited because they 

 stain the matrix; but some material can be stained in bulk with an 

 aqueous stain while the material is in water, or with an alcoholic stain 

 while passing through the alcohols. Safranin is good for xylem, alum 

 carmine is more generally useful, and borax carmine is good for some 

 animal tissues. A second stain, like Delafield's haematoxylin, which 

 can be extracted from the matrix, can be used after the sections have 

 been cut. 



