SPECIAL METHODS. 317 



spread them on a slide, pour a few drops of the methylene-blue 

 solution over them, and after a few moments wash off the dye with 

 water and cover the section. If such rapid work is not necessary, 

 the sections can be fixed in formalin (page 287), and, after washing 

 out that reagent, stained. Such sections may be hardened and de- 

 hydrated by placing them in dishes of increasingly strong alcohols, 

 and finally mounted in dammar ; but the results are by no means so 

 good as when fixation and hardening are done before sections are cut. 

 When time is not pressing, the following method will give good 

 results : 



1. Fix and harden pieces not over \ inch thick in absolute alcohol 

 kept absolute with anhydrous cupric sulphate. This will take from 

 four to twelve hours, according to the sizes of the specimens. 



2. Dip the specimen in thick collodion and embed it on a glass 

 block by the rapid method. When the block has been in 80 per 

 ■cent, alcohol for three or four hours it may be cut ; but it is better 

 to let the collodion harden for twenty-four hours. If a paraffin 

 microtome is available, remove the alcohol with chloroform, renewed 

 at least once. If the specimens are small, two to four hours will 

 suffice for this step in the process. Half an hour each in chloroform 

 saturated with paraffin and in fresh melted paraffin in the oven will 

 accomplish sufficient impregnation with paraffin, and the specimen 

 can then be embedded by the box method. 



3. Stain with hematoxylin and eosin, cutting short the time of 

 washing after the hematoxylin, if in a hurry. 



4. Dehydrate in 95 per cent, alcohol ; two successive baths. 



5. Clear in carbol-xylol. 



6. Mount in xylol-dammar. 



When paraffin has been used, follow the directions given on 

 pages 294 and 297. 



Very serviceable sections can be prepared in less than twenty- 

 four hours by these methods, and the specimens, though not of the 

 best quality, will be permanent, and may be kept for future refer- 

 ence. The paraffin method may yield excellent permanent mounts 

 in eight to ten hours if the pieces are small. 



Special Methods. 



The foregoing methods are for the preparation of sections of soft 

 tissues. It is sometimes desirable to separate the tissue-elements by 

 .some process of maceration, or to prepare sections of calcified tissues, 



