lilLLlNG. 13 



drop of water in a watch-glass or on a slide, and heated over the flame 

 of a spirit-lamp. For large objects, the water or other liquid employed 

 as the vehicle of the heat may be heated beforehand and the animals 

 thrown into it. 



As soon as it is supposed that the protoplasm of the tissues is coagu- 

 lated throughout, the animals should be brought into alcohol (30 to 70 

 per cent, alcohol) (if water be employed as the heating agent). 



An excellent plan for preparing many marine animals is to kill them 

 in hot fresh-water. Some of the larger Nemertians ai'e better preserved 

 by this method than by any other with which I aui acquainted. 



14. Slowly Contracting Animals.— Animals that contract 

 but slowly^ such as Alcyonium and Veretillum, and some 

 Tunicates, such as Pyroftoma, are very well killed by throw- 

 ing them into some very quickly acting fixing liquid, either 

 used hot or cold. Glacial or very strong acetic acid (van 

 Beneden's method) is an excellent reagent for this purpose ; 

 it may be used, for example, with some Medusas. After an 

 immersion of a few seconds or a few minutes, according to 

 the size of the animals, they should be brought into alcohol 

 of at least 50 per cent, strength. Lemon juice employed in 

 this way has given me very good results with small Annelids 

 and Hirudinea. Corrosive sublimate is another excellent 

 reagent for this purpose. 



Narcotisation. 



15. Narcotisation is performed by adding some antesthetic 

 substance very gradually, in very small doses, to the water 

 containing the animals, and waiting patiently for it to take 

 effect slowly. 



The Tobacco-smoke Method for ActiniEe, of Lo Bianco (Jena 

 Zeit. Naturw., Bd. xiii, 1879, p. 467; Mitth. Zool. Stat. Neapd, Bd. ix, 

 1890, p. 499), is : — A dish containing the animals in water is covered with 

 a beU-glass, under which passes a curved glass or rubber tube, which 

 dips into the water. Tobacco smoke is blown into the water for some 

 time through the tube, and the animals are then left for some hours 

 overnight. As soon as it is observed that the contraction of u, tentacle 

 does not begin until a considerable time after it has been irritated by 

 a needle, a quantity of some fixing liquid sufficient to kill the animals 

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



16. Nicotin in solution may be used {A^r>ii:ES, Atti R. Ac cad. 

 dei Lincei, v, 1880, p. 9). Andres employs a solution of 



