SECTION STAINING 111 



Bunsen and the preparation laid on it, the coin being 

 re-heated as often as required. The stain may be pre- 

 vented from flooding the slide by confining it between 

 grease-pencil lines as described for films (p. 107). After 

 staining, the sections are well rinsed in distilled water 

 and then slightly decolorised by rinsing for half a minute 

 or so in a watch-glass of 1 per cent, acetic acid in distilled 

 water. They are then again washed and passed as rapidly 

 as possible through alcohol, cleared in xylol, and mounted. 

 Carbol-methylene blue or carbol-thionine blue may be 

 used instead of the Lofner's solution, the staining taking 

 from a few minutes to half an hour. If a contrast stain 

 be desired the sections may be treated for a few seconds 

 with the eosin solution after the dilute acetic. If staining 

 be prolonged evaporation must be prevented. In the 

 case of a section mounted on the slide and flooded with 

 stain, the slide should be placed on a piece of wet 

 blotting-paper on a tile and covered with the lid of a 

 Petri dish. 



The micro-organisms in sections stained with Loffler's 

 blue are very liable to become decolorised unless the 

 dehydration is expeditiously performed. To avoid this 

 Unna's method may be adopted. After staining and 

 decolorising with acidulated water as described, the 

 sections are placed on the slide (if not already mounted 

 thereon), gently warmed, and so dried ; they are then 

 treated with xylol and mounted in balsam. The tissue 

 elements, however, are apt to suffer. 



A better method is, after decolorising with the dilute 

 acid, to dehydrate with anilin instead of with alcohol, 

 the section being treated with fresh anilin two or three 

 times, then with a mixture of equal parts of anilin and 

 xylol, and finally with two or three baths of xylol. 



