ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
525 
fineness, and about 2 feet long, 4 in. in diameter at one end, and 
2 at the other. Fasten a tin ring to the small end and attach 
the large end to the mouth of the bottle. Then put on your rubber 
boots and go to the pond. There pour the water into the small end of 
the muslin tube, holding it up for that purpose, the bottle hanging 
below. It will rapidly strain out the .Rotifers, &c., which will finally 
get down into the bottle, and as the muslin tube has so large a surface 
the water will run through quickly, all solid matters collecting in the 
bottle. Less is lost by the use of the muslin tube than by a funnel- 
shaped strainer, and the cloth will not become clogged.” 
Test-tube Holder for Microscopical Investigations.* — Dr. D. von 
Sehlen has invented a test-tube holder, the advantages of which are 
mainly its stability and simplicity. Hence it will be found of great use 
in the cultivation of the various forms of Fungi, and also for photo- 
Fig. 58. 
graphic purposes. The apparatus consists of a flat oblong frame R 
which supports two uprights, placed equidistant from the ends of the 
frame. In these uprights a triangular piece is cut out in order to put 
the test-tube in, and the latter is kept in position by the two spring- 
clamps F. The distance between the two spring-clamps is enough to 
allow sufficient space for the objective to work in, and the length of the 
frame such that it is easily clamped to the Microscope-stage. It is 
hardly necessary to explain that the test-tube is easily moved round its 
short axis, and pushed up and down, so that when on the Microscope- 
stage it is easily illuminated from below. 
Preparation of Nutritive Agar.f — Dr. V. A. Moore writes:— 
“ The extent to which nutritive agar is employed in the cultivation of 
Bacteria renders it of much importance that its method of preparation 
should be made as perfect as possible. When it is prepared after the 
method recommended in works on bacteriology (which is practically the 
same as that first formulated by Koch for the preparation of solid culture 
media), a medium is obtained that favours the growth of most germs. 
In this respect the method is desirable, but in regard to the other 
* Zeitschr. f. Wiss. Mikr., vii. (1890) pp. 17-20 (2 figs.)l 
f Amer. Mon. Micr. Journ., xi. (1890) pp. 115-7. ° 9 
