CH. VII} 



SERIAL SECTIONS 



191 



ORDER OF PROCEDURE IN MAKING MICROSCOPICAL PREPARATIONS BY THE 



PARAFFIN METHOD 



$ 300. It will be seen from this table aiid from sections 283 to 299, that it re- 

 quires from 2 to 7 days to get a microscopical preparation by the paraffin method 

 if one starts with a fresh tissue. Depending on the method of fixing and harden- 

 ing, the time may be much greater. Much time will be lost in waiting unless one 

 plans ahead in histological work. 



1. Fixing and hardening the tissue or 10. 



organ ( 284), 4 days or more. 



2. Dehydrating the object to be cut in j n. 



95% r stronger alcohol (| 285), 12. 

 i to 24 hours containing %% j 

 eosin. (301). 13. 



3. Displacing the alcohol and clearing 



tissues with cedar-wood oil. (See \ 14. 

 286), 2 to 24 hours. 



4. Infiltrating the tissue with paraffin j 15. 



in the paraffin oven (| 286), 2 to \ 



24 hours. 16. 



5. Imbedding in paraffin ( 287), 10 



minutes. 



6. Cutting the sections (I 288), 10 j 17. 



minutes. 



7. Extending the sections with warm 18. 



water. (See I 289). 



8. Fastening the sections to a slide j 19. 



( 290), 5 minutes to 24 hours. 



9. Removing the paraffin ( 291), 10 20. 



minutes to 24 hours. 



Removing the xylene or benzin 



(3 292). 



Washing with water, note, p. 180. 

 Staining with an aqueons dye 



(\ 294), 2 minutes to 24 hours. 

 Washing away the superfluous 



stain with water ( 294). 

 Staining with a general dye ( 295- 



296), 10 seconds to 10 minutes. 

 Washing the sections with water 



( 295-296). 

 Dehydrating the stained sections in 



95% alcohol (\ 297), 3 minutes to 



24 hours. 



Clearing the sections ( \ 298) 2 min- 

 utes to 24 hours. 

 Mounting in Balsam ( 299), i to 5 



minutes. 

 Labeling the preparation ( \ 308) , 2 



minutes. 

 Cataloging the preparation ( \ 309), 



5 to 10 minutes. 



SERIAL SECTIONS : IN TOTO STAINING. 



$301. In histological studies it is frequently of the greatest advantage to 

 have the sections in serial order, then an obscure feature in one section is fre- 

 quently made clear by the following or preceding sections. While serial sections 

 are very desirable in histological study, they are absolutely necessary for the solu- 

 tion of morphological problems presented in complex organs like the brain, in 

 embryos and in minute animals where gross dissection is impossible. 



For all sections whether serial or otherwise, if the sections are to be stained 

 on the slide it is of great advantage to have the object stained in toto in eosin- 

 during the dehydration (see 2 of the table above), Very thin sections and minute 

 parts of embryos then show in the ribbons. The eosin bulk staining does not in 

 any way interfere with the subsequent staining of the sections. 



