Il6 METHODS OF COLLECTING AND PRESERVINGT 



Holothiirians, siieli 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 ISTemathelminths, 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 5 per cent, chromic acid : this last method 

 may be also applied to Uirudinea. 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 Hermellidm, Aphroditidce, and the Eunicidte, 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 tliem to 

 protrude wholly or partly from their tubes. 



