436 SOME ZOOLOGICAL METHODS. 



after death, the mantle is generally injured, and it is im- 

 possible to get the foot and siphon into the extended state. 

 DE CASTELLARNAU (La Estacion Zoolog. de Napoles, Madrid, 

 1885) advises that they be killed by the method of EISIG and 

 ANDEES described for ActiniaB in 12. Before dying, the 

 animals protrude largely their feet, siphons, branchiae, and 

 tentacles, and die with their shells open. They may be fixed 

 as soon as insensibility has supervened, by bringing them into 

 picro-sulphuric acid, or some other rapidly killing fixing 

 agent. 



In order to demonstrate the absence of the supposed aquiferous pores in 

 the root of Lamellibranchiata, FLEISCHMANN (Zeit.f. wiss. ZooL, xlii, 1885, 

 p. 376) proceeds as follows : A mussel is quickly seized at a moment when 

 the foot is fully extended, and the two valves of the shell are forcibly 

 pressed together, so as to prevent any flowing back towards the interior of 

 the liquid contained in the foot. The foot may then be fixed by holding it 

 for a few minutes in hot sublimate solution. 



The same methods recommended for Lamellibranchiata 

 sometimes give good results with Gastropoda. The asphyxia- 

 tion method has been described in 19. 



S. Lo BIANCO advises that Lamellibranchiata, Prosobran- 

 chiata, and, amongst the Heteropoda, Atlantidae, be narcotised 

 with 70 per cent, alcohol, 12. Opisthobranchiata ought not 

 to give much trouble, and I recommend sudden killing with 

 liquid of Perenyi, or the acetic acid method, 811.* 



For Pteropoda in general, liquid of Perenyi. Creseis is a 

 difficult form. S. Lo BIANCO advises the alcohol method, 

 12. 



Note the hydro xylamin method of HOFEE, 16; also 

 BEOCHEB'S monobromated camphor, 811. 



814. Terrestrial Gastropods. The asphyxiation method has 

 been described in 19. 



The quantity of mucus that exists in the integument of Gastropoda is 

 often a serious obstacle in the way of preparation. MARCHI (Arch. f. mik. 

 Anat., 1867, p. 204) finds that if a living Limax be thrown into moderately 

 concentrated salt solution it will throw off enormous quantities of mucus, 

 and die in a few hours. The epidermis will be found well preserved. If 



* Aplysia may first be narcotised by subcutaneous injection of about 1 c.c. 

 of a 5 to 10 per cent, solution of hydrochlorate of cocain (ROBERT, Bull. 

 Scient. de la France, &c., 1890, p. 449 ; Zeit. f. wiss. Mik., ix, 2, 1892, 

 p. 216). 



