VARIOUS SOFT-BODIED INVERTEBRATE ANIMALS. 109 
Holothurians, such as Thyone and Cucumaria, after the tentacles 
are fully expanded, should be seized a little below the bases of the 
tentacles by forceps, using a slight pressure, and the anterior 
portion of the body should then be immersed in concentrated acetic 
acid. Alcohol (90 per cent.) should then be injected into the mouth, 
and the specimens placed in 70 per cent, alcohol. The injection 
should be repeated each time the alcohol is changed. 
Synapta should be fixed by immersion in a tube containing a 
mixture of equal parts of sea-water and ether (or chloroform), where 
they remain completely expanded. They should then be washed for 
a short time in fresh- water, and passed into alcohol, taking care to 
increase the strength of this very gradually. 
Some collectors use formalin, but this fluid is to be avoided for 
Echinoderms. 
Vermes. 
Cestodes, Trematodes, Turbellaria, as well as Nemathelminths, are 
most satisfactorily killed with corrosive sublimate, either cold or hot. 
Sagitta, however, succeeds best in copper sulphate and sublimate or 
chrom-osmic mixture. 
Nemerteans should be narcotized in a solution of chloral hydrate 
in sea-water 1 per cent., where they should remain for from six to 
twelve hours. They are then to be hardened in alcohol. Gephyreans 
may be narcotized with 1 per cent, solution of chloral hydrate in sea- 
water, or in alcoholized sea-water, from three to six hours ; or may 
be killed at once in 0"5 per cent, chromic acid : this last method 
may be also applied to Hirudinea. Chsetopods are best narcotized 
in sea-water containing 5 per cent, of absolute alcohol, or by adding 
gradually to the surface of the sea-water in which they are 
contained a mixture of glycerine 1 part, 70 per cent, alcohol 2 parts, 
and sea-water 2 parts, hardening them subsequently in alcohol. 
The Hermellidce, Aphroditidce, and the Eunicidce may be killed in 
cold corrosive sublimate. Some of these, such as Diopatra, should, 
however, be narcotized in alcoholized sea-water. 
Serpulidce, before treatment with corrosive sublimate, should be 
narcotized in 1 per cent, chloral hydrate, which causes them to 
protrude wholly or partly from their tubes. 
