422 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Preserving Caprellidae.* * * § — P. Mayer finds that these animals may be 
preserved without shrivelling by placing them in a mixture of glycerin 
1 part and 50 per cent, spirit 2 parts after they are taken from the 
alcohol in which they have been kept. The alcohol is then slowly 
evaporated with moderate heat. The author considers that balsam is 
contra-indicated since on account of its strong refraction the finer 
skeletal details are imperfectly seen. 
Mode of studying free Nematodes.f — Mr. N. A. Cobb collects from 
sand by applying his knowledge of the fact that, in standing water, 
sand sinks at once, while small organisms sink rather slowly. “ Put 
half a pint of sand with a pint of water into a dish of the form and size 
of an ordinary one quart fruit-tin. Having a second beaker or fruit-tin 
at hand empty, pour the water and sand rapidly back and forth until the 
water is well roiled, then suddenly stop ; the sand at once sinks to the 
bottom of the dish, but the organisms remain for a few seconds partially 
suspended. The instant the sand reaches the bottom of the dish, pour 
the supernatant fluid containing the organisms into a third dish and 
there let it stand until clear, when the sediment of organisms may be 
obtained in a very satisfactory state by decanting the clear water.” In 
collecting from mud the process must be reversed. 
If the animals are to be studied in the living state they may be 
rendered motionless by adding a little chloral hydrate to the water. If 
glycerin preparations are to be made, kill with 1/100 to 1/10 osmic 
acid and allow the worms to remain in it till they become a trifle 
coloured. It is best to use warm weak osmic acid. 
For the very finest histological as well as coarser anatomical work 
Mr. Cobb has devised a method which gives far better results than any 
other with which he is acquainted. 
Mode of examining Calcareous Bodies of Alcyonacea-t — Dr. G. v. 
Koch says that the easiest way of examining these bodies is to cut a 
polyp through longitudinally with the scissors, to spread out in 
glycerin, cover with cover-glass, and observe with crossed nicols. The 
spicules will appear white on a dark ground and are generally very 
distinct. The same method may be employed with particles of 
coenosarc. 
Demonstrating Structure of Siliceous Sponges.§— Herr F. C. Noll 
succeeded, by treating with nitrate of silver, in showing that the spicules 
of Desmacidon Bosei were covered with an organic layer, the exact 
origin of which would appear to be uncertain. The same reagent was 
used with advantage in examining Spongilla. Small pieces of sponge 
were suspended on the slide in the aquarium, and when they had pro- 
perly spread themselves out, were treated for about twenty minutes with 
0 • 25 per cent, silver nitrate, and afterwards stained with picrocarmine. 
The flat epithelium was by this means well preserved. For imbedding, 
* Fauna u. Flora d. Golfes v. Neapel, Monogr. xvii. (1890) pp. 157 (7 pis.). See 
Zeitschr. f. Wiss. Mikr., vii. (1891) p. 501. 
t Proc. Linn. Soc. N.S.W., v. (1890) pp. 450-2. 
X Mittheil. Zool. Stat. Neapel, ix. (1891) p. 655. 
§ Abhandl. d. Senkenbergischen Naturf. Gesellsch., xv. (1888) pp. 1-58 (3 pis.). 
See Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 497-8. 
