96 COLLODION AND OTHER IMBEDDING METHODS. 



that is more transparent and of a better consistency for cutting (Zeit. 

 iviss. MiL, vi, 1889, p. 164). 



Imbedding masses of excellent quality can be prepared with 

 ordinary collodion, but celloidin furnishes more readily solutions of 

 known concentration. Otherwise there is but little to choose 

 between the two, and therefore in this work the terms collodion and 

 celloidin are used in different ly. 



According to UNNA (Monatschr. p. Dermatol., xxx, 1900, pp. 422 and 

 476 ; Zeit. wiss. Mik., xviii, 1901, p. 32) a more inelastic, and therefore 

 better, mass is obtained by adding to celloidin 2 per cent, of oil of 

 turpentine, stearate of soda, or (best of all.) castor oil. Celloidin with 

 this addition has been put on the market under the name of " Celloi- 

 dinum inelastrcum," by the Chemische Fabrik vorm. E. Schering, in 

 Berlin. 



Photoxylin (KRTSINSKY, VIRCHOW'S Archiv, cviii, 1887, p. 217 ; 

 BUSSE, Zeit. wiss. Mik., ix, 1892, p. 47) is a dry substance, of the aspect 

 of cotton-wool, and chemically nearly related to celloidin. It can be 

 obtained from GRUBLER. It gives a clear solution in a mixture of 

 equal parts of ether and absolute alcohol, and should be used in exactly 

 the same way as celloidin. It has the advantage of affording a mass 

 which after hardening in 85 per cent, alcohol remains perfectly trans- 

 parent. Some writers say that it gives a better consistency, but others 

 deny this (APATHY, e.g.) 



TSCHERNISCHEFF (Zeit. wiss. Mik., xvii, 1900, p. 449) recommends 

 Colloxylin (10 grms. dissolved in 10 grms. of eugenol or clove oil, with 

 the addition of 50 c.c. of ether and 1 of absolute alcohol). 



The Older Celloidin Method. 



158. Preparation of Objects.- -The objects must first be very 

 thoroughly dehydrated with absolute alcohol. They are then soaked 

 till thoroughly penetrated in ether, or, which is better, in a mixture 

 of ether and absolute alcohol. DUVAL (loc. cit.) takes for this 

 purpose a mixture of ten parts of ether to one of alcohol ; SCHIEFFER- 

 DECKER (and the majority of workers) a mixture of equal parts of 

 ether and alcohol ; TUBBY (in Nature, November 17th, 1892, p. 51) 

 advises a mixture of four parts of ether and one of alcohol. FISH 

 advises acetone, see next . MANN (Methods, etc., p. 172) takes 

 equal parts of ether and methyl alcohol. 80 also PAVLOW, Zeit. 

 wiss. Mikr.j xxi, 1904, p. 15. 



This stage may be omitted if the objects are of a sufficiently 

 permeable nature, and they may be brought direct from alcohol into 

 the collodion bath. 



159. The Collodion Bath.- -The secret of success here is to infiltrate 

 the objects first with thin solutions, then with the definitive thick 



