FREEHAND SECTIONS 91 



gential sections. It is wasteful to use three slides and three covers to 

 show these three views, or to make a mount containing only a single 

 section of the rhizome of Pteris. 



Put the label at the left. Write first the genus and species; then 

 indicate what part of the plant has been mounted. The date on which 

 the material was fixed is often valuable. In many cases, the date of 

 collecting the material is desirable. The beginner is likely to write also 

 the stains used, and other details, which he will find quite unnecessary 

 after a little experience. Figure 18 illustrates a good style of labeling 

 and mounting. 



The following is a convenient summary of the foregoing processes, 

 beginning with the sections in 95 per cent alcohol : 



1. Sections in 95 per cent alcohol. 



2. Safranin, 12-24 hours. 



3. Fifty per cent alcohol, with or without acid, until color is right, generally 

 about 2-10 minutes. 



4. Water, 5 minutes, changing frequently. 



5. Delafield's haematoxylin, 3-30 minutes. 



6. Water, 5-10 minutes, changing frequently. 



7. Water slightly acidulated, 5-10 seconds. 



8. Water, to wash out acid, 20-30 minutes. 



9. Fifty per cent alcohol, 5 minutes. 



10. Ninety-five per cent alcohol, 5 minutes. 



11. One hundred per cent alcohol, 5 minutes. 



12. Xjdol, 5 minutes. 



13. Balsam. 



14. Cover and label. 



If clove oil seems necessary, finish as follows: 



12. Clove oil, 2-5 minutes. 



13. Xylol, 5 minutes. 



14. Balsam. 



15. Cover and label. 



Another method has given excellent results, especially with old 

 stems, pieces of dry boards,' etc. Cut pieces 5-10 mm. square and 2-3 

 cm. long, boil in water 10-24 hours and, when cool, transfer to equal 

 parts of 95 per cent alcohol and glycerin. Material may be left in this 

 mixture indefinitely. Hard woods should remain here for at least two 

 weeks before cutting, since the mixture is a good preservative and 

 hard woods left in it for a year are easier to cut. 



