FOR ZOOLOGICAL PURPOSES. I25 



hydrate in sea water of one part in i,ooo. After six to twelve hours 

 they are hardened in alcohol in long zinc boxes with a layer of wax 

 at the bottom, being placed in extended position with a glass rod or 

 similar implement, and if necessary fixed with pins stuck in the wax. 

 In some cases the process may be much shortened by employing 

 chloral hydrate at a strength of i per cent. 



Sdi^iffa may be well fixed in a mixture of lo per cent, solution of 

 sulphate of copper loo parts, sublimate saturated ten parts, or in 

 chromic acid i per cent. loo parts, osmic acid i per cent, two parts. 



Leeches, e.g., Pontobdella, are to be killed in chromic acid \ per 

 cent., extending them with a pin at each end in a dish with a wax 

 bottom. 



Polychaeta, the more common marine worms of which so many 

 species occur everywhere, succeed well when anaesthetized in a 

 mixture of five parts of alcohol to loo sea- water. They are to be 

 left in this until they lose sensibility, which takes from two to twelve 

 hours, and then may be hardened in alcohol 70 per cent., or in 

 chromic acid i per cent. It is well to harden them first of all in a 

 dish with wax bottom where they can be straightened, and to finish 

 ihem in long glass tubes. They should be finally preserved in 

 alcohol of 90 per cent. Worms which live in tubes must be carefully 

 extracted before they are killed. Serpulids and some others can be 

 made to quit their tubes by being placed in chloral hydrate one per 

 I, coo, after which they are placed in cold saturated solution of corro- 

 sive sublimate and then washed in fresh water. 



Crustacea. — ^The larger Decapods, such as crabs, are to be 

 killed first in fresh water, care being taken not to leave them after 

 they are dead, and are then placed directly in alcohol 70 per cent. 

 The hermit-crabs {Paguridce) should be transferred several times to 

 fresh alcohol, and finally kept in 90 per cent. 



Amphipods and Isopods can be placed directly in alcohol of 70 

 per cent. 



To prepare Cirripedia such as Lepas (the Barnacle), they are 

 allowed to die in 35 per cent, alcohol, when in most cases the cirri 

 will remain extended ; if not they can be gently pulled out with 

 forceps. Balaniis (the Acorn Barnacle) is placed directly in 70 per 

 cent, alcohol. 



Copepoda and marine Cladocera such as Evadne, Schizopoda 

 such as ATysis, the larvae of Decapods, and even the smaller adults 

 such as the shrimp, l/ippolyie, etc., are best killed with saturated 



