Freehand Sections 85 



9. 50 per cent alcohol, 1 minute. 



10. 95 per cent alcohol, 1 minute. 



11. 100 per cent alcohol, 5 minutes. 



12. Xylol, 1 to 5 minutes. 



13. Balsam. 



14. Cover and label. 



If clove oil seems necessary, finish as follows: 



12. Clove oil, 2 to 5 minutes. 



13. Xylol, 1 to 5 minutes. 



14. Balsam. 



15. Cover and label. 



Since it usually happens that processes are commenced, but 

 cannot be completed at a single laboratory period, it is necessary 

 to know where sections may be left for several hours or until the 

 next day without suffering injury. At 1, 2, or the pure water of 8 in 

 the schedule above given, sections may be left until the next day. If 

 it is not desirable to mount all of the sections which have been pre- 

 pared, they may be kept indefinitely in clove oil or xylol. If the 

 sections are to remain for a year or more in the clearing agent, xylol 

 is to be preferred. Shells with good corks are best for keeping such 

 material. 



For the study of vascular anatomy, this is the most permanent 

 stain which has come into general use. 



More recently, safranin combined with anilin blue or with 

 light green has been coming into favor. Both these methods will be 

 described. 



Safranin and Anilin Blue. Use the alcoholic safranin already 

 described, and a 1 per cent solution of anilin blue in 90 per cent 

 alcohol. 



With this combination we should recommend a long stain in 

 safranin, not less than 24 hours. Wash in 50 per cent alcohol, but 

 do not extract all the safranin from the cellulose walls. Stain 2 to 10 

 minutes in anilin blue. Rinse a few seconds in 95 per cent alcohol, 

 then treat for about 5 seconds with 95 per cent alcohol slightly 

 acidulated with hydrochloric acid. The weak blue should at once 

 change to a bright blue and, at the same time, the acid will remove 

 some of the safranin. It is for this reason that we proceed while 



