KILLING. 13 



night. Next morning they should be irritated from time to time by touch- 

 ing a tentacle with a needle. As soon as it is observed that an animal 

 begins to react slowly that is to say, as soon as it is found that the contrac- 

 tion of the tentacle does not begin until a considerable time after it has 

 been irritated by the needle the narcotisation may be considered sufficient. 

 It may be further completed, if desired, by the addition of a little chloro- 

 form. A quantity of some fixing liquid sufficient to kill the animals before 

 they have time to contract is then added to the water. 



14. Nicotin in solution may be used instead of tobacco smoke 

 (ANDRKS, Atti R. Accad. dei Lincei, v, 1880, p. 9 ; see Journ. 

 Roy. Mic. Sue., N. S., ii, 1882, p. 881). Andres employs a 

 solution of 1 gramme of nicotin in a litre of sea water. The 

 animal to be anaesthetised is placed in a jar containing half 

 a litre of sea water, and the solution of nicotin is gradually 

 conducted into the jar by means of a thread acting as a 

 siphon. The thread ought to be of such a thickness as to 

 be capable of carrying over the whole of the solution of 

 nicotin in twenty-four hours. See also Mitth. Zool. Stat. 

 Neapel, Bd. ii, 1880, p. 123. 



15. Chloroform may be employed either in the liquid state 

 or in the state of vapour. KOROTNEFP (Mitth. Zool. Stat. 

 Neapel, v, Hft. 2, 1884, p. 233) operates in the following 

 manner with Siphonophora. The animals being extended, 

 a watch-glass containing chloroform is floated on the surface 

 of the water in which they are contained, and the whole is 

 covered with a bell-glass. As soon as the animals have 

 become insensible they are killed by means of hot sublimate 

 or chromic acid solution plentifully poured on to them. 



Liquid chloroform is employed by squirting it in small 

 quantities on to the surface of the water containing the 

 animals. A syringe or pipette having a very small orifice, so 

 as to thoroughly pulverise the chloroform, should be employed. 

 Small quantities only should be projected at a time, and the 

 dose should be repeated every five minutes until the animals 

 are anaesthetised. 



I have seen large Medusae very completely anaesthetised in 

 the state of extension in an hour or two by this method. 

 ANDRES finds that this plan does not succeed with Actiniae, 

 a- \vith them maceration of the tissues supervenes before 

 anaesthesia is established. 



