130 CHAPTER IX. 



the methods described below, in the chapter on " Serial 

 Section Mounting." 



Masses that have been cleared before cutting with cedar 

 oil, or the like, may be cut dry, 165. 



160. Staining. The sections may now be stained as desired* 

 either loose, or mounted in series on slides or on paper as 

 described in the chapter on " Serial Section Mounting." It 

 is not in general necessary, nor indeed desirable, to remove 

 the mass before staining, as it usually either remains colour- 

 less, or gives up the stain on treatment with alcohol. But 

 some of the anilin dyes and some other colours stain it strongly, 

 .and are not removed with sufficient completeness by the pro- 

 cesses of dehydration and clearing. If it be desired to 

 employ these, the mass may be removed by treating the 

 sections with absolute alcohol or ether. 



161. Clearing and Mounting. You may mount in glycerin 

 without removing the mass, which remains as clear as glass 

 in that medium. 



You may mount in balsam, also, without removing the 

 mass, which does no harm, and serves the useful purpose of 

 holding the parts of the sections together during the 

 manipulations. Dehydrate in alcohol of 95 or 96 per cent, 

 (not absolute, as this attacks the collodion). NIKIFOEOW 

 (Zeit. f. wiss. Mik., viii, 2, 1891, p. 189) recommends a mix- 

 ture of equal parts of alcohol and chloroform. Clear with 

 a substance that does not dissolve collodion. The clearing 

 agents most recommended are origanum oil (01. Origan. 

 Cretici, it is said, should be taken, not 01. Orig. Gallici ; 

 but see as to this reagent the remarks in Chap. VI, 113), 

 bergamot oil (said to make sections shrink somewhat), oil of 

 sandal-wood, lavender oil, oil of cedar-wood (safe and gives 

 excellent results, but acts rather slowly), chloroform, xylol, or 

 benzol (may make sections shrink if not well dehydrated), or 

 Dunham's mixture of three or four parts of white oil of 

 thyme with one part of oil of cloves. (As to oil of thyme, 

 see also " Origanum Oil" in Chap. VI, 113.) 



FISH (Proc Amer. Mic. Soc., 1893) advises a mixture of 

 one part of red oil of thyme with three parts of castor oil, 

 the latter being added in order to counteract the volatility 



