180 SERIAL SECTION MOUNTING. 



commends that the slide be one that has been previously pre- 

 pared with a layer of collodion, if it is desired to stain on the 

 slide; but if not, a clean slide is perfectly sufficient. The 

 slide may of course be treated with ether vapour in a prepara- 

 tion glass or similar arrangement. 



326. Apathy's Oil of Bergamot Method (Mitth. Zool. 8 tat. 

 Neapel, 1887, p. 742; Zeit. f. wiss. Mik., v, 1, 1888, p. 46, 

 and v, 3, 1888, p. 360; Journ. Roy. Mic. floe., 1888, p. 670). 

 Cut with a knife smeared with vaselin ( 296) and wetted 

 with 95 per cent, alcohol. Float the sections, as cut, on 

 bergamot oil (must be green, must mix perfectly with 90 per 

 cent, alcohol, and must not smell of turpentine). The sec- 

 tions spread themselves out on the surface of the oil ; before 

 they sink, each one is pushed by means of a needle into its 

 place 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 on to 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 

 sections 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. 



