4 CHAPTEE I. 



1892, p. 892. See also Schumzb [Zeit. wiss. Mile, ii, 1885, p. 537) ; and 

 SnsuKi, ibid., 1909, p. 211 ; Kolsteb (ibid., xvii, 1900, p. 294). 



The " Siebdosen," or sieve-dishes of Stbinach, Zimmeemann, and 

 SucHANNEK (vide Zeit. wiss. Mile, iv, 1887, p. 433, and vii, 1800, p. 158), 

 are viseful for many purposes. They are sent out in a very neat fonn 

 by Griibler and Co. See also Tischatkin, ibid., xxiii, p. 45. rAiECHiLD s 

 perforated porcelain cylinders for washing (ibid., xii, 1896, p. 301) seem 

 to be a very neat idea. See also the similar device of Schafpee (ibid., 

 xvi, 1900, p. 422 ; Joura. Boy. Mic. /S'oc, 1900, p. 394). For Ewald's 

 section-washing apparatus, see Zeit. Biol., xxxiv, 1897, p. 264. 



That of SCHOEBEL (ibid., XX, 1903, p. 168) is simple and efficient; as 

 also that of Kkiegbaum (ibid., xxvii, 1910, p. 504). 



A capillary siphon for the aspiration of liquids in the fixing, staining- 

 and washing of suspended blood-coi'puscles, sperm-cells, protozoa, and 

 the like, is described by Ev^ald, ibid., p. 253. 



It is sometimes stated that it is necessary that the last 

 alcohol-bath should consist of absolute alcohol. This, how- 

 ever, is incorrect, a strength of 95 per cent, being sufficient 

 in most cases. For the small amount of water that remains 

 in the tissues after treatment with these grades of alcohol is 

 efficiently removed in the bath of clearing agent if a good 

 clearing agent be employed. Oil of cedar will remove the 

 remaining water from tissues saturated with 95 per cent, 

 alcohol; oil of bergamot will "clear" from 90 per cent, 

 alcohol, and anilin oil will clear from 70 per cent, alcohol. 



I am not aware of any substance that can entirely take 

 the place of alcohol for dehydration and preservation. Ace- 

 tone and methylal have been substituted for alcohol in the 

 dehydration of methylen-blue preparations (Paekee, Zool. 

 Ann., 403, 1892, p. 376), and anilin oil can be made to 

 dehydrate watery sections if they be first mopped up with 

 blotting-paper ; but a really efficient substitute for alcohol 

 in general work remains yet to be discovered. 



4. Preservation. — Considered as a mere dehydrating agent, 

 alcohol fulfils its functions fairly well. But considered as a 

 histological preservative agent, it is far less satisfactory. If 

 tissues be left in alcohol for only a few days before further 

 preparation, injurious effects will perhaps not be very dis- 

 agreeably evident. But it is otherwise if they are put away 

 in it for many weeks or months before the final preparation 

 is carried out. The dehydrating action of the alcohol being 

 continuously prolonged, the minute structure of tissues is 



