ANESTHETICS 361 



cipitate consists of cocaine, and is soluble in alcohol or in an 

 excess of picric acid. The safest plan to insure good fixation 

 and at the same time to get rid of the precipitate is to remove 

 the specimen to another vessel and add more fixative. 



Menthol. — This substance is now much used, and with great 

 success, for anaesthetizing the larger marine animals. 



The animals are put into a clean vessel, with sufficient sea 

 water to cover them well, and the surface of the water is 

 strewn with crystals of menthol. As the menthol dissolves 

 the animals expand, and eventually become quite anaesthe- 

 tized. In from twelve to twenty-four hours they may be 

 transferred to a suitable fixing fluid in which they will be 

 preserved with little, if any, contraction. Anemones, Holo- 

 thurians, Ascidians, and many Molluscs have been successfully 

 treated in this way. 



Alcohol. — Seventy per cent, alcohol, added drop by drop 

 to sea water in which marine animals are living, will often 

 cause them to die in an expanded condition. The rate at 

 which the drops are added varies in different cases, and no 

 definite rules can be given. 



Chloretoneis recommended by Bigelow as a most satisfactory 

 anaesthetic for medusae and siphonophores . A 1 per cent. 

 solution is used, and a small quantity is added to the sea water 

 containing the specimens. 



II. NOTES ON STORING SPECIMENS. 



Bottles with Cork Stoppers. — Bottles and tubes are 

 generally sold with inferior corks, which are often per- 

 forated with small holes. It is advisable to order 

 corks of a good quality, such as are used in chemical 

 laboratories ; bungs and shives should be avoided. A 

 good cork makes an excellent stopper, provided that 

 it fits nicely and is well driven in. For a cork to grip 

 firmly, a bottle with a slightly tapering neck is required, 

 a little wider at the bottom than at the top, so when 

 the cork swells it cannot slip out. The ordinary 

 straight glass tube requires a cork with straight sides, 

 and the cork should be well squeezed before being 



