106 COLLODION AND OTHER IMBEDDING METHODS. 



saturated with paraffin, added in shavings at a temperature not exceed- 

 ing 20 to 23 C. The tissues are prepared by soaking in some of the 

 mixture of alcohol and toluene, and are then penetrated with the 

 celloidin -paraffin solution. The mass is hardened in a saturated solution 

 of paraffin in chloroform or in toluene, and is finally imbedded in pure 

 paraffin in the usual way. 



STEPANOW imbeds in paraffin after clearing with benzol, last . 



JORDAN, after imbedding as in last , passes through a bath of paraffin 

 dissolved in chloroform into pure paraffin. 



WILHELMI (Fauna Flora Golf. Neapel, xxxii, 1909, p. 17), following 

 APATHY, imbeds in celloidin, hardens in chloroform, then adds benzol 

 to the chloroform, and passes through pure benzol (half an hour to an 

 hour) into paraffin, and cuts dry. 



Similarly, BRECKNER, Zeit. wiss. Mik., xxv, 1908, p. 29. 



STERLING (Jena Zeit., 1909, p. 253) soaks for two or three days in 

 equal parts of clove oil and collodion, puts for a couple of hours (until 

 clear) into xylol, and imbeds in paraffin. 



See also DAHLGREN, Journ. Appl. Microsc., 1898, p. 97 ; SABUSSOW, 

 Mitth. Zool Stat. Neapel, xii, 1896, p. 353 ; MEYER, ibid., xiv, 1901, 

 p. 295 ; MITROPHANOW, Arch. Zool. Exper. (3), 3, 1896, p. 617 ; 

 FEDERICI, Anat. Anz., xxi, 1907, p. 602 ; BORDAGE, Bull. Sci. France 

 Belg., xxxix, 1905, p. 385 ; GANDOLFI, Zeit. wiss. Mik., xxv, 1909, 

 p. 421 ; MAYER, ibid., xxiv, 1907, p. 132. 



Other Cold Masses. 



172. Lead-Gum Imbedding Method of J. SALKIND (C. R. Soc. de 

 Bid., t. Ixxix, 1916, No. 16). The principle of this method is that 

 an aqueous solution of gum treated by acetate of lead, when exposed 

 to the action of ammonia, is transformed into a gel, sufficiently stiff 

 to allow of thin sections being cut. 



(1) Dissolve a quantity of gum of cherry (white for preference) in 

 double its weight of aq. dest. After nitration, add to the solution 

 one-third its volume of the liquid subacetate of lead (extract of 

 Saturne), to which has been added 5 per cent, of glacial acetic acid. 

 This gives a kind of thin collodion-like solution, in which you place 

 the pieces at room temperature, to be imbedded, after a fixation, 

 for which see below. 



(2) Leave about twelve hours for pieces about a millimetre in 

 thickness : larger pieces must be left longer. After the correct 

 period has elapsed, you let the lead gum solution evaporate in the 

 air till the solution reaches the consistency of a thick celloidin 

 solution. 



(3) Arrange the pieces to- be imbedded in a paper box (or on a 

 piece of paper), in a large drop of the thick solution. Expose to 

 strong ammonia vapour for about five minutes till the block hardens 

 to the consistency of cartilage. 



