1897] MICROSCOPICAL JOURNAL. 199 



may be at once transferred to the solution of acacia and 

 sug-ar and frozen. Or, as sug-g-ested by H. Pleng-e the 

 piece may be placed in a 4 per cent formal-dehyde solu- 

 tion for a quarter-of-an-hour, and then frozen in the same 

 solution. 



When the tissue has been prepared in some such man- 

 ner, or even when perfectly fresh, it is placed with some 

 formol and g-um acacia fluid upon the specimen-holder of 

 the microtome, and a small stream of chloride, methyl 

 chloride or anestile (a mixture'of these two re-agents) is 

 played from above directly upon the specimen. 



The tube containing the ethyl chloride is held about a 

 foot from the specimen, and moved from place to place 

 until the specimen is firmly attached to its base of support 

 and the upper portion is coated with a few crystals of ice. 

 These crystals are extremely small and delicate, and, 

 therefore, do not injure the tissue so markedly as in some 

 other of the freezing- methods. The specimen is readily 

 frozen in from 30 seconds to a minute. Sections are then cut 

 and placed in v^^ater or fifty per cent alcohol, and mounted 

 in the usual way. Excellent stained preparations may be 

 prepared in fifteen minutes or less from the time that the 

 tissue is removed from the body. 



BACTERIOLOGY. 



Differentiation of the B-. coli from the B. typhi abdo- 

 minalis. — Eisner (Zeitsch. f. Hyg-. XXI.) uses plates pre- 

 pared with Holtz's potato gelatine, to which, after it has 

 been made slightly acid, 1 per cent of iodide of potash has 

 been added. Even on this unfavorable medium the B. coli 

 gfrows freely and quickly, but no colonies of the B. typhi 

 abdominalis are visible for 48 hours, and they appear as 

 extremely fine small, shining- patches, like drops of water. 

 Controling his experiments by PfeifTer's immune-serum 

 process, Eisner always obtained positive results from 

 typhoid stools. Piorkowski, at the Berlin Medical Society 

 June 10, 1896, reported experiments in cultivating these 

 bacilli on agar, bouillon, and g-elatine mixed with urine, 



