248 THE AMERICAN MONTHLY [Aug 



The process is as follows :-— Make a small paper box, 

 about a-hali'-an-inch square, and fill it with the white of an 

 egg. Eliminate all alcohol from the material which is to 

 be mounted, and embed it in the albumen. Expose the 

 box and its contents to heat, and when hardened place it 

 again in alcohol. If the sections are passed through oil 

 of cloves with balsam, the albumen will become clear 

 and transparent. 



Bacteriology. — An illustration of the pitfalls that con- 

 front science students is given by Dr. Martin Ficker, a 

 Grerman bacteriologist. Among various sources of error 

 in work with bacteria is the glass of the vessel used, as 

 different kinds of glass impart varying degrees of alkalin- 

 ity to water, and it is found that some bacteria, notably 

 those of cholera, are favorably affected by alkalinity. 

 This novel cause seems responsible for marked and im- 

 portant discrepancies. 



Mites.-— Freshwater mites do not, as a rule, make sat- 

 isfactory mounts. They shrink and fade, thus losing in 

 the preserved state the beautiful symmetry and colorings 

 which render them, when alive, such charming objects for 

 observation and study. The difficulty is the mounting 

 medium. No formula is known which will give perfect- 

 ly satisfactory results, but the following, if carefully pre- 

 pared, will enable the microscopist to preserve his speci- 

 mens, for some years at least, from bleaching and col- 

 lapse : — Prepare three mixtures of distilled water and 

 pure glycerine in the proportions of twelve parts, ten 

 parts, and eight parts of water, respectively, to one part 

 of pure glycerine, and to the last add a small drop of car- 

 bolic acid. Place the specimens in the twelve-part mix- 

 ture and leave them for twelve hours, after which place 

 them in the ten-part mixture and leave them for a simi- 

 lar period. They may now be permanently mounted in 

 the third mixture. Solid glass cells are preferable to 

 built-up ones. 



