Stains and Staining 43 



8. Haematoxylin. 



Many objects, like the archegonia of gymnosperms and the 

 embryo-sacs of angiosperms, will stain sufficiently in 5 or 6 hours; 

 algae require at least 20 hours. 



9. Wash in water, 5 minutes, changing as often as the water shows 

 any color. 



10. Iron-alum, 2 per cent solution. 



No time can be indicated here. The preparation must be 

 watched under the microscope. After some experience, one can 

 form some judgment from the color tone, as the slide stands in the 

 Stender dish of iron-alum, but the finishing must always be done 

 under the microscope. If the stain is coming out rather slowly, as 

 it should, one can handle 6 to 10 slides at one time. Put the slides 

 on a 5X7 glass plate and put the plate on the stage of the micro- 

 scope. The iron-alum can be added or removed with a pipette. 

 As slide after slide reaches the proper differentiation, it is placed 

 in water. 



11. Water, 30 minutes. 



The water should be changed several times. If this washing 

 is not thorough, the preparation will fade, on account of the con- 

 tinued action of the iron-alum. If an aqueous counter-stain is 

 used, apply it at this point. 



12. 35, 50, 70, 85, 95, 100 per cent alcohol, 5 minutes in each. 



If an alcoholic counter-stain is used, apply it near the alcohol of 

 the same strength as the stain. 



13. Absolute alcohol and xylol, equal parts, 5 minutes. 



14. Xylol, 2 to 5 minutes. 



15. Balsam. 



Sharp's Schedule.- 



1. Remove the paraffin with xylol. 



2. Rinse in absolute alcohol. 



3. 95 per cent alcohol. 



4. 50 per cent alcohol. 



5. Water. 



6. If osmic acid has been used in fixing, place the slides in 10 per cent 

 solution of peroxide of hydrogen in water until bleached. 



7. Water. 



8. Iron-alum, 2| per cent, 2 to 3 hours. 



9. Wash well. 



10. ^ per cent haematoxylin, 24 hours. 



11. Wash in water. 



12. Extract the stain in 1 per cent iron-alum, watching the process 

 under the microscope. 



