ORDER OF PROCEDURE IN MAKING MICROSCOPICAL PREPARATIONS BY 

 THE COLLODION METHOD. 



S 265. It will be seen from this table, and sections 252-266, that 

 it requires about five days to get a microscopical preparation if one com- 

 mences with the fresh tissue. Other methods of hardening might re- 

 quire as many months. It is evident, therefore, that one must exercise 

 foresight in histology or much time will be wasted. 



i. Fixing and hardening the tissues 

 (§ 252), 4 days or more. 



2. Dehydrating the object to be cut in 



95% or stronger alcohol (§ 253), 2- 

 24 hours. 



3. Saturating the tissue in ether-alcohol 



(J 254), 2-24 hours. 



4.- Infiltrating with thin collodion 

 d 2 S5)i 2 hours to 2 days. 



5. Infiltrating in thick collodion (? 256), 



5 hours to several days. 



6. Imbedding the tissue (§ 257), 15 to 



20 minutes. 



7. Hardening the collodion with chlo- 



roform ({j 258), 5-24 hours. 



8. Clarifying and further hardening the 



collodion with castor- xylene (ji 258), 

 10-36 hours. 



9. Cutting the sections (J 259), 10 min- 



utes to 2 hours. 



10. Transferring the sections to a slide 



with paper (g 260), 1 minute. 



11. Fastening the sections to the slide 



with ether-alcohol (§ 261), 1 or 2 

 minutes. 



12. Removing the oil from the sections 



with benzin and alcohol (% 262), 3-5 

 minutes, or 24 hours. 



13. Staining the sections with an alco- 



holic dye (§ 263-264), 2 minutes to 

 24 hours. 



14. Staining the sections with an aque- 



ous dye (§ 264), 2-10 minutes. 



15. Removing the superfluous dye by 



washing in water or alcohol ($ 263- 

 264), 2-5 minutes. 



16. Staining with a general dye (J 264), 



15-30 seconds. 



17. Washing with water or alcohol 



(§ 263-264), 1 to 2 minutes. 



18. Dehydrating the sections in 95% al- 



cohol (g 266), 5 min. to 24 hours. 



19. Clearing the sections (§ 266), 5 min. 



to 24 hours. 



20. Draining the sections, 1-2 minutes. 



21. Mounting in Canada balsam (§ 266), 



1-2 minutes. 



22. Sealing the cover-glass (§ 238), 2 



minutes. 



23. Labeling the preparation (§ 291), 2 



minutes. 



24. Cataloging the preparation ($ 294), 



5-10 minutes. 



