1218 The American Naturalist. [December, 
normally. I have thus been able to obtain excellent material for the 
Ascidians, and I have made successful cultures of many kinds of 
Annelid larvze."' 
Preservation of Siphonophora.'—Bedot proceeds as follows: 
The colony is immersed in a 15—20 per cent. aqueous solution of sul- 
phate of copper. At the same time sea-water is poured in along with the 
colony, in such bulk that the copper solution is ten times as great. 
After fixation, which happens in a few minutes, a few drops of nitric 
acid are added to the solution, and the mixture is gently stirred up 
with a glass rod, in order to prevent the formation of any precipitate. 
After four or five hours the preparation is to be further hardened in 
Flemming’s mixture : 
EIG Se ts Ger OP |. 1... .. . 15 pats. 
Bee): s slve ros 4 parts. 
old ee a Re I part. 
This fluid should be allowed to act twenty-four hours, and should be 
twice the volume of the copper solution. A few drops of 25 per cent. 
alcohol are next added to the fluid, and the quantity and strength of 
the alcohol gradually increased, until in fifteen days 70 per cent. may 
be used, and finally go per cent. 
For Tracing Nerve Fibres in the Brain.’—For the study of 
the finer structure of the fore-brain of Amphibia, Oyarzun recom- 
mends Golgi's silver method, as improved by Ramon y Cajal (Anat. 
. V., 3, 1890, p. 85). The brain is treated hr twenty-four 
hours in the following mixture (kept dark) : 
Bichromate of potash (3 put cent. aqueous solution) 20 parts. 
E i S Der Cent este P Rd 5 parts. 
After washing some seconds, the preparation is placed in silver ni- 
trate solution, which should be renewed once; it is then exposed to 
the light. The silver solution consists of 
This solution is followed after twenty-four hours by alcohol, to com- 
plete the hardening. 
* Arch. Sci, Phys. et Nat., XXI., 1889, p. 556; Jour. Roy. Mic. Soc., Dec. 1889, p. 832- 
5 Oyarzun. Arch. f. Mik. Anat. XXXV., 3. 1890, p. 380. 
