132 CHAPTER IX. 



thereby greatly simplifying the operation of cutting. By 

 GILSON'S ingenious Rapid Method, the time necessary for 

 hardening is very greatly abridged, and the whole series 

 of operations becomes almost as short and simple as the 

 paraffin method. I cannot imagine that anyone who has 

 ever employed the new method would willingly go back to 

 the old one. The following paragraphs describe the new 

 method. 



163. The New Method, by Clearing before Cutting 1 . This 

 process is due, I believe, in the first instance to E. MEYER 

 (Biol. Centrall)., x, 1890, p. 508), who advised soaking blocks 

 beFore cutting for twenty-four hours in glycerin. BUMPDS 

 (Amer. Anat., xxvi, 1892, p. 80 ; see Journ. Roy. Mic. Soc., 

 1892, p. 438) advises clearing the mass, after hardening in 

 chloroform, with white oil of thyme or other suitable clear- 

 ing agent (see above, 161). The knife is wetted with the 

 clearing oil, and the same oil is employed for covering the 

 exposed surface of the object after each cut. Similar recom- 

 mendations are made by EYCLESHYMKK (op. cit., pp. 354, 

 563), carbolic acid, or glycerin, or the mixture given 161, 

 being* suggested for clearing ; and Professor GILSON has for 

 a, long time past adopted the practice of clearing before 

 cutting with cedar oil, as described in the next . 



FISH (loc. cit., 161) also advocates the practice of clear- 

 ing in the mass, recommending' the clearing mixture there 

 given. Similarly GAGE, Trans. Amer. Mic. Soc., xvii, 1896, 

 p. 361. 



All the authors above quoted cut in the wet way, that is 

 to say, with a knife wetted with the clearing liquid. I have 

 found a great improvement in cutting* dry, and in employing 

 the combined hardening and clearing process of GILSON, 

 given below. 



164. GILSON'S Rapid Process (communicated by Professor 

 G-ILSON, April, "1892). The object is dehydrated, soaked in 

 ether, and brought into a test-tube with collodion or thin 

 celloidin solution. The tube is dipped into a bath of melted 

 paraffin, and the collodion allowed to boil (which it does at 

 a very low temperature) until it has become of a syrupy con- 

 sistence. (It should be boiled down to about one third of its 



