244 THE CELL 



small sliding microtome and a sharp razor are necessary. Cut one 

 of the pieces of collodion into an oblong block with the imbedded 

 material near one end. This can be clamped in the microtome, be- 

 ing held in place by a flat piece of cork on either side. The collodion 

 must project above the cork. The razor should be adjusted in such 

 a manner that the whole length of the blade is used in cutting. The 

 blade should be tilted downwards so that only the cutting edge 

 comes in contact with the block which should not be scraped by the 

 lower flat surface of the razor back of the edge. Both the collodion 

 block and the razor must be kept flooded with alcohol during the 

 process of cutting. When several sections have been cut they may 

 be floated out on a slide and arranged near the center. Then with 

 a pipette place a drop of ether on the sections. This partially dis- 

 solves the 'collodion and thus sticks the sections to the slide. The 

 slide is then covered with water to remove the alcohol, after which 

 it is ready for staining. Sections are ruined if allowed to become 

 dry at any time after cutting. 



4. Stain with hematoxylin for from three to five minutes, and 

 wash off the surplus stain with water. 



5. Drain off the water and dehydrate by keeping the slide flooded 

 with alcohol for ten minutes, or by placing it in a vessel of alcohol. 



6. Pour off the alcohol and cover the slide with a clearing mix- 

 ture (see p. 241) and allow it to stand for ten minutes. The clearer 

 removes the alcohol which cannot mix with balsam. 



7. Drain and wipe off as much of the clearer as possible with- 

 out touching the sections. Then place a small drop of prepared 

 Canada balsam on the sections near the center of the slide, and with 

 a pair of forceps lay on a clean cover-glass. If the proper amount 

 of balsam has been used it will spread out to the edge of the cover- 

 glass without exuding. The slide is now ready to be examined. It 

 should be cleaned and labelled and put away in a small wooden box 

 which is furnished by dealers in microscopical supplies. 



Box of microscope slides, and a packet of collodion drying in a glass vessel. 



