l.\!i;UI>DIN<; MKTllOliS. S7 



bergamot. They are taken one by one on the point of a knife, and after 

 the excess of oil has been drawn oft', are transferred each to a drop of 

 the collodion mixture, in which they will stay in any required position. 

 When half a dozen or more objects have been oriented in reference to 

 the cross lines (which are to be parallel to the section planes) the \\lx.l.- 

 thing is placed in turpentine. This washes out the clove oil and fixes 

 the objects very firmly to the paper. The paper with the attached 

 objects is now passed through the bath of paraffin and imbedded in the 

 usual way. After cooling 011 water the block is trimmed and the paper 

 peeled off, leaving the objects in the paraffin close to the uiider-surt'are 

 of the block. This surface is now seen to be marked by the orienting 

 lines of the ribbed paper, and also by any record numbers which may 

 before imbedding have been written with a soft pencil on the paper. 



KNOWEN (Jotu-n. Morph., xvi, 1900, p. 507) takes smooth paper and 

 engraves parallel lines on it with a needle, and takes xylol instead of 

 turpentine. 



A somewhat more complicated form of this process has b-n 

 described by WOODWORTH, Ball. Mus. Comp. Z >oL. xxxviii, vol. xxv. 

 1893, p. 45. 



A similar process has also been described by FIELD and MARTIN in 

 Zeit. iviss. Mik., xi, 1891, p. 11, small strips of gelatin being used instead 

 of paper. 



MAYER also (Grundziige, LEE and MAYER, 1910, p. 89) takes strips of 

 photographic gelatin, and lets the collodion set in benzol. 



HOFFMANN (Zeit. wiss. Mik., xv, 1899, p. 312, and xvii, 1901, p. I!-'!) 

 takes, instead of the ribbed paper, glass slips ruled with a diamond, and 

 completely imbeds the objects in large drops of clove oil collodion 

 (equal parts), allowed to stand for twenty-four hours in an open vessel. 

 The drops are caused to set in xylol. See also SAMTER, ibid., xiii, 1897. 

 p. 441 ; JORDAN, Ibid., xvi, 1899, p. 33; and PETER, Vcrli. Anat. GV*., 

 xiii Vers., 1899, p. 134. 



ENTZ (Arch. Protistenk., xv, 1909, p. 98) orients in clove oil collodion 

 on a cover-glass coated with paraffin, and puts the whole into chloroform 

 in which the mixture sets into a sheet which can be detached. 



DENNE (Jo urn. Appl. Mic., iii, 1902, p. 888) imbeds on disks of paper 

 held at the bottom of glass tubes containing the paraffin by bent wires, 

 by means of which a cylinder of paraffin containing the object may In- 

 lifted out as soon as cool. 



WILSON (Zeit. wins. Mik., xvii, 1900, p. 109) makes orientation lines by 

 imbedding alongside the objects strands of osmium-blackened nerve- 

 fibres. See also a further development by Wilson, ibid., xxvii, 19K. 

 pp. 228 and 231. 



143. Cooling the Mass. -Whatever method of imbedding 

 and orientation in the molten paraffin 1ms been employed, 

 the important point no\v to be attended to is tlmt //"' jmnifjin 

 be cooled rapidly. The objeet of this is to prevent crystalli- 



