146 CHAPTER X. 



xii, 2, 1895, p. 154 (Journ. Roy. Mic. Soc.. 1895, p. 702) ; Zeit.f. wiss. Mik., 

 xiv, 1, 1897, p. 39. 



187. The Shellac Method (GIESBRECHT, Zool Am., 1881, p. 484). 

 Prepare a stock of slides covered with a thin and even film of shellac. This 

 is done as follows : Make a not too strong solution of brown shellac in abso- 

 lute alcohol, filter it thoroughly ; warm the slides, and spread over them a 

 layer of shellac by means of a glass rod dipped in the solution and drawn 

 once over each slide. Let the slides dry. 



You may now either take a prepared slide and brush it over very thinly 

 with creasote applied by means of a brush, and arrange the sections on the 

 sticky surface ; then heat the slide on a water-bath for about a quarter of 

 an hour at the melting-point of the paraffin the slide is allowed to cool, 

 and the paraffin is dissolved away bj dropping turpentine on to the sections, 

 which are then mounted in Canada balsam. Or (MAYER, Intern. Monatsschr. 

 /. Anal., etc., 1887, Heft 2 ; Zeit. f. wiss. Mile., iv, 1, 1887, p. 77) the 

 brushing with creasote is omitted and the sections are arranged on the dry 

 film and gently pressed down on to it, then exposed for half a minute to 

 vapour of ether, which fixes them. 



The method does not allow of staining on the slide, and is in my opinion 

 superfluous, but see further details in previous editions, or Mitth. d. Zool. 

 Stat.,\u, 1881, p. 148 ; Journ. Roy. Mic. Soc. (N. S.), vol. ii, 1882, p. 888 ; 

 WHITMAN'S Methods in Microscopical Anat., p. 117 ; CALDWELL, Quart. 

 Journ. Mic. Soc. (N. S.), Ixxxvii, 1882, p. 336 ; P. MAYER, Amer. Natural, 

 1882, p. 733 ; Zeit.f. wiss. Mik., iv, 1, 1887, p. 77 ; Journ. Roy. Mic. Soc., 

 1885, p. 910 ; and LEE und MAYER, Gh'undzilge, etc., 1898, p. 118. 



188. VAN WALSEM'S Gelatin Process. Extremely complicated. See 

 Zeit. f. wiss. Mik., xi, 2, 1894, pp. 229 to 235, or Journ. Roy. Mic. Soc., 

 1895, p. 122. 



189. OBREGIA'S process given below, 196, for celloidm 

 sections, is also applicable to paraffin sections. 



For BLOCHMAN'S modification of Weigert's process, by means of which 

 large sections can be preserved unmounted, see Zeit. f. iviss. Mik., xiv, 2, 

 1897, p. 189. 



For other methods with gum, gelatin, etc., suppressed as superfluous, see 

 previous editions. 



Methods for Watery Sections. 



190. Foi/s Gelatin (FoL, Luhrl., p. 132). Four grammes 

 of gelatin are dissolved in 20 c.c. of glacial acetic acid by 

 heating on a water-bath and agitation. To 5 c.c. of the 

 solution add 70 c.c. of 70 per cent, alcohol and 1 to 2 c.c, of 

 5 per cent, aqueous solution of chrome-alum. Pour the mix- 



