APATHY'S OIL OF BERGAMOT METHOD. 219 



This method is especially useful for sections made under 

 water, large celloidin sections amongst others. 



335. POLI (Malpighia, ii, 1888, 2, 3 ; Zeit. f. wiss. Mik., v, 3, 

 1888, p. 361) arranges sections on a layer of melted Kaiser's 

 gelatin (supra, 294), adds glycerin, and covers. See. also 

 supra, 333. 



336. Frenzel and Threlfall's Gutta-percha (or Caoutchouc) 

 Method (Zool. Anz., 1883, pp. 51, 301, and 423). This extremely elegant 

 method is not perfectly safe ; the gutta-percha film being liable to tear ; and 

 is now, I believe, very generally abandoned. 



Methods for Celloidin Sections. 



337. Summers' Ether Method (Amer. Hon. Mic. Journ., 1887, 

 p. 73; Zeit. f. wiss. Mik., iv, 4, 1887, p. 482; Journ. Roy. 

 Mic. Soc., 1887, p. 523). Besides the method given above 

 ( 325), which is applicable to celloidin sections, but is 

 needlessly complicated, Summers recommends the following 

 simpler method : Place the sections in 95 per cent, alcohol 

 for a minute or two, arrange on the slide, and then pour over 

 the sections sulphuric ether vapour, from a bottle partly full 

 of liquid ether. The celloidin will immediately soften and 

 become perfectly transparent. Place the slide in 80 per cent, 

 alcohol, or even directly in 95 per cent, if desired. The 

 sections will be found to be firmly fixed, and may be stained 

 if desired. 



SCHIEFFERDECKEB (Zeit. f. iviss. Mik., v, 4, 1888, p. 507) re- 

 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. 



338. Apathy's Oil of Bergamot Method (Mitth. Zool. Stat. 

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

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

 Cut with a knife smeared with vaselin ( 303) and wetted 

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

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

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

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

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



