220 SERFAL SECTION MOUNTING. 



on a slip of tracing-paper dipped into the oil. (A good size 

 for the paper is about as broad as the slide, and three times 

 as long as the cover.) When the requisite number of sections 

 has been arranged on the paper, you drain the paper, dry the 

 under side of it with blotting-paper, turn it over, and gently 

 press it down with blotting-paper onto a carefully dried slide. 

 Remove the paper by rolling it up from one end. The sections 

 remain adhering to the slide, and may have the remaining 

 bergamot oil removed from them by means of a cigarette 

 paper. If they are already stained, nothing remains but to 

 add balsam and a cover. 



In the case of unstained or very small objects, it is well to add a little 

 alcoholic solution of safranin to the bergamot oil. The celloidin of the sec- 

 tions becomes coloured in it in a few seconds, and makes them readily visible. 

 The colour disappears after mounting in a few days. 



If the sections are to be stained, the slide after removal of 

 the bergamot oil is exposed for a few minutes to the vapour 

 of a mixture of ether and alcohol, then brought into 90 per 

 cent, alcohol, and after a quarter of an hour therein may be 

 stained in any fluid that contains 70 per cent, alcohol or more. 



If it be desired to stain in a watery fluid, care must have 

 been taken when arranging the sections to let the celloidin of 

 each section overlap that of its neighbours at the edges, so 

 that the ether vapour may fuse them all into one continuous 

 plate. This will become detached from the slide in watery 

 fluids, and may then be treated as a single section. 



339. Apathy's Series-on-the-Knife Method (Zeit. f. wiss. Mik., 

 vi, 2, 1888, p. 168). The following is in some respects more 

 convenient than the oil of bergamot method. The knife is 

 well smeared with yellow vaselin rubbed evenly on with the 

 finger, and is wetted with alcohol of 70 to 90 per cent. As 

 fast as the sections are cut they are drawn with a needle or 

 small brush to a dry part of the blade, and there arranged in 

 rows, the celloidin of each section overlapping or at least 

 touching that of its neighbours. The rows are of the length 

 of the cover-glass, and are arranged one under the other so 

 as to form a square of the size of the cover-glass. When a 

 series (or several series, if you like) has been thus completed, 

 the sections are dried by laying blotting-paper on them 

 (there is no risk of their becoming attached to it, as they are 



