THE MOLLUSC A 967 



For purposes of dissection either fresh or alcoholic specimens 

 may be used. Live specimens may be killed by plunging them 

 into boiling water for a few seconds. The animal can thus be 

 removed from the shell in the usual way, using great care not to 

 mutilate it with the hook; or the shell, if not too heavy, can be 

 carefully broken away with the forceps. Preserved specimens are 

 frequently difficult to extract from the shell, in which case the shell 

 must be removed either by breaking or, if too thick, by dissolving 

 it in muriatic acid. 



^'Two pairs of fine scissors will be necessary, one pair with straight 

 points, the other with curved points; one or more fine scalpels, and 

 two pairs of fine forceps, one straight and the other curved. Dis- 

 secting needles are also necessary. These can be made by forcing 

 the heads of fine needles, by means of a pair of pliers, into the end 

 of a round stick of small diameter. The point of one of these 

 needles should be bent so as to form a hook, first heating the end 

 of the needle to a white heat." 



*'In dissecting the animal, a circular china dish about 4 inches 

 in diameter and 2 in depth will be necessary; also a piece of sheet 

 cork as large as will lie at the bottom of the dish, fastened to a 

 thin sheet of lead with either string or rubber bands. It is best 

 to have the lead of the same size as the cork. This leaded cork 

 is to be placed in the bottom of the dish, and the dish filled with 

 alcohol. If the animal has once been placed in alcohol, all dissec- 

 tions should be made in alcohol, but freshly killed specimens may 

 be dissected in water, and many of the organs at this time present 

 a much more natural appearance than when acted on by alcohol. 

 Place the animal on the cork and fasten it down with small pins, 

 or better yet, with very fine, short needles inserted through the 

 margin of the foot. Then with a fine pair of scissors, commencing 

 at the head, cut through the integument along the center of the 

 back, taking care not to injure any of the organs below. The 

 integument is now to be removed from the dorsal part, turned 

 back and fastened to the cork, removing the needles from the 

 margin of the foot and putting them through the edges of the 

 integument. All the organs of the anterior part of the snail are 



