1MBRDDING METHODS. 101 



understand the description is not clear). Blocks are then cut out 

 and hardened in absolute alcohol (suspended therein) for several days 

 (1 day per millimetre of thickness), cleared in terpinol (1 day per 

 millimetre), and cut with a knife wetted with the same. Said to give 

 sections of 3 p, without the least shrinkage. 



BRUNOTTI'S Gold Gelatin Mass (Journ. de Botan., vi, 1892, 

 p. 194). Twenty grms. gelatin dissolved with heat in 200 c.c. 

 distilled water, and 30 to 40 c.c. of glacial acetic acid with 

 1 grin, corrosive sublimate added after filtering. Objects 

 are prepared by soaking in some of the mass diluted with 

 two to three volumes of water, then imbedded in the 

 undiluted mass. The mass is then hardened in spirit or 

 bichromate of potash, picric acid, or the like. No heat at 

 all is required in this process. 



NICOLAS'S Method (Bibiogr. Anat., Paris, 3 annee, 1896, 

 p. 274). Preparations are first soaked for one or two days 

 in a 3 per cent, to 4 per cent, aqueous solution of gelatin 

 kept at 25 C., then for the same time in a 10 per cent, 

 solution, and then for two or three days more in a 20 per 

 cent, to 25 per cent, solution containing 8 per cent, to 10 

 per cent, of glycerin and kept at 35 C. They are then 

 imbedded in some of the same mass in paper trays, and as 

 soon as the gelatin has set are thrown into a mixture 

 of formol 1 part, water 7. After a few days therein 

 the gelatin has become hard and insoluble, and may be cut 

 or preserved for months in weak formol solution, or dilute 

 alcohol or glycerin, or even in pure water. Sections must 

 be very gradually passed through successive alcohols for 

 dehydration, as they curl up very easily. They, however, 

 flatten out at once on being brought from absolute alcohol 

 into cresylol, and may then be mounted in balsam. To 

 mount in glycerin is of course easy. 



BUEZYKSKI (Polu. Arch. Biol. Med. Wiss., i, 1901, p. 39) 

 finds that alkaline formol hardens gelatin better than acid. 



GASKELL (Journ. Path. Bact., July, 1912, p. 58) soaks in 

 pure gelatin, melted s.a., for two to five hours at 37 C., 

 and hardens the mass in vapour of formol, for three or more 

 days. To cut, he freezes. He mounts in glycerin jelly, to 

 avoid dehydration and shrinkage. 



