1 6 JOURNAL OF CONCHOLOGY. 



ON THE CIRCUMSTANCES ATTENDING DEATH, 

 BY DROWNING, OF HELIX ASPERSA. 



By Dr. J. W. WILLIAMS, M.A. 



(Read before the Conchological Society, May 2nd, 1888, and recommended for publication 

 by the referee, Rev. A. H. Cooke). 



When one of the MoUusca is required in an expanded con- 

 dition for anatomical purposes, it is usual to kill it by drowning 

 in water. This process occupies generally about two days, and 

 as the Mollusca are known to be extremely tenacious of life, 

 even when deprived of oxygen, it occurred to me that a note 

 containing observations of the phenomena attending drowning, 

 and observations of an autopsy made immediately succeeding 

 death, would not be uninteresting to those conchologists who 

 are interested, as I am, in their physiology. Consequently, re- 

 quiring dead expanded specimens of Helix aspersa for anatomical 

 work, I placed several in a cylindrical glass, lilled completely with 

 water and tightly sealed so as not to admit air, on the morning 

 of April 28th, and noted the following results. At first the 

 ommatophores are not fully extended — the retractor muscles, 

 which were plainly visible, keeping, probably under the influence 

 of reflex actions, the apices of the tentacles invaginated to a slight 

 extent, on account of, no doubt, the extreme sensitiveness of 

 the cornea to water ; the pulmonary aperture opens and closes 

 normally, but, after the lapse of two or three hours, the action 

 becomes slower and slower, and finally ceases in an expiration ; 

 the penis, if everted, is seldom returned back again to its general 

 position in the cavity of the prostoma ; the whole of the pros- 

 toma on its upper surface becomes of a lighter cinereous colour, 

 the purplishness of the proximal extremity gradually disappears, 

 the whole swells up with fluid absorbed from the water, the 

 reticulation with the tuberculae in the areolae of the meshes be- 



J.C, vi., Jan., i88g. 



