ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
255 
filter should he freed of albuminous matter by passing distilled water 
through several times, after which the bougie may be sterilised in an 
autoclave. If purified in this way, bougies can be used a long time 
without firing them. With a one bougie filter it is easy to get 3-5 litres 
of fluid in 24 hours. 
Easy Method of Preparing Serum Agar.* — Messrs. A. A . Kantliack 
and J. W. Stephens use ascitic, pleuritic, or hydrocele fluid for making 
serum-agar. The procedure is as follows : — To every 100 ccm. of the 
exudate 2 ccm. of a 10 per cent, solution of caustic potash is added. To 
this is added 1 • 5-2 per cent, agar previously soaked in acidulated water, 
and the mixture boiled until the agar is dissolved. The fluid is then 
hot-filtered, and to the filtrate 4 to 5 per cent, of glycerin should be 
added. After this it is poured into test-tubes and sterilised. The addi- 
tion of 0 * 5-2 per cent, of grape sugar in no way improves this mixture as 
a cultivation medium. Before adding the caustic potash to the serous 
fluid a small quantity of the latter should be boiled in a test-tube, and in 
case it should be highly albuminous, when it will set solid, the serum 
should be diluted with at least twice its bulk of distilled water, and then 
to every 100 ccm. of the diluted fluid 2 ccm. of KOH and 1 • 5-2 grm. 
of agar are to be added. Unless this precaution be adopted the whole 
mass will gelatinise and be useless. 
Improved Solid Watch-Glass. | — Dr. A. C. Mercer describes an im- 
proved form of solid watch-glass which, when a series is superimposed, 
Fig. 56. Fig. 57. 
makes a secure pile. The size, shape, and method of using may be easily 
gathered from the illustrations. The writing (fig. 57) is not intended to 
be permanent. 
* Lancet, i. (1895) pp. 835-6. 
t Trans. Amer. Micr. Soc., xvii. (1896) pp. 371-f (3 figs.). 
