202 COLLODION AND OTHER IMBEDDING METHODS. 



described below. It is not in general necessary, nor indeed 

 desirable, to remove the mass before staining, as it usually 

 either remains colourless 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 suffi- 

 cient completeness by the processes of dehydration and 

 clearing. If it be desired to employ these, the mass may be 

 removed by treating the sections, either loose in a watch-glass, 

 or mounted on a slide with Mayer's albumen (which will, 

 however, generally hold the stain just as obstinately as the 

 collodion), with absolute alcohol or ether. 



305. 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 mixture 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. Oretici should be taken, not 01. 

 Orig. Gallici ; but see, as to this reagent, the remarks in 

 Chap. XVIII, 348), 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 benzin (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. XVIII, 348.) 



Some specimens of clove oil dissolve collodion very slowly, and may be 

 used, but I would not be understood to recommend it. The action of origanum 

 oil varies much, according to the samples ; some sorts do not clear the collo- 

 dion, others dissolve it, others pucker it. MINOT (Zeit.f. wiss. Mik., iii, 2, 

 1886, p. 175) says that Dunham's mixture "clarifies the sections very readily 

 and softens the celloidin just enough to prevent the puckering, which is so 

 annoying with thyme alone." 



Carbolic acid has been recommended. WEIGEET (Zeit. f. wiss. Mik., iii, 

 4, 1886, p. 480) finds that a mixture of 3 parts of xylol with 1 part of 

 carbolic acid (anhydrous) clears well. But it must not be used with the 



