126 THE PKliSERWMlON OK MARINE ANIMALS 



solution of sublimate. They may be taken out of the sea water 

 separately with a pipette, or may be filtered out by means of fine 

 muslin, or may be killed by simply adding the sublimate solution to 

 the water in which they are swimming, afterwards decanting the 

 mixture and replacing it with pure sublimate solution. Whenever 

 sublimate is used for killing, the specimens should be washed for a 

 long time, e.g., an hour, in fresh water before being placed in alcohol. 



MoUusca. — Lamellibranchs must be narcotized in sea water 

 and alcohol (5 parts of the latter to 100 of former), remaining in 

 it six to twelve hours, by wh'ch time they will usually be insensible, 

 with the foot and siphons extended ; then they can be transferred to 

 70 per cent, alcohol. It is well to place a piece of wood between 

 the valves of the shell to prevent them closing again. 



(iasteropods, such as Patella, Buccinum (whelk), etc., are to be 

 treated in the same way. Another method which succeeds well with 

 some species oi Natica, and with Nassa and Trochus, is to place the 

 animals for some days in a mixture of sea water and fresh water in 

 equal parts, and then fix them with acetic acid. 



Among Opisthobranchs Elysiidse and Eolididai are to be killed 

 suddenly with pure acetic acid poured over them while expanded in 

 a small quantity of sea water, and as soon as they are dead they must 

 be transferred to weak alcohol. 



Doris and allied forms must be first narcotized by adding 70 per 

 cent, alcohol to the sea water containing them, and then suddenly 

 killed with a flood of acetic acid or boiling sublimate. Large speci- 

 mens of Tritonia are to be placed in fresh water to which are added 

 some drops of acetic acid till they are dead, and are then placed in 

 chromic acid \ per cent. 



Cephalopoda. — The Octopods, such as Eledone or Octopus, are 

 killed in chromic acid i per cent., in which they remain half an hour 

 to two hours ; they are then washed in fresh water, from which they 

 are transferred to alcohol 70 per cent., changed repeatedly. Decapods, 

 such as Lflligo, Sepia, Sepiola, can be fixed in the same way, or 

 directly in alcohol 70 per cent., care being taken to draw out the two 

 tentacular arms as soon as the animal is dead. 



Polyzoa. — Many species can be killed in the expanded con- 

 dition, like Hydroids, with a flood of hot solution of corrosive sub- 

 limate. Other methods which sometimes succeed better are adding 

 70 per cent, alcohol to the sea water, or placing the specimens in 

 chloral hydrate, i per thousand, before placing them in sublimate. 



