GENERATIVE SYSTEM. 527 



part of the animal ; and as, in the superior animals, the kidneys are the 

 only organs which, in a state of health, secrete uric acid, and as the 

 calcareous sac of the Snails has many other anatomical relations with 

 the kidneys, Mr. Jacobson concludes that this sac represents the kid- 

 neys, and must be so considered in all the Mollusca which are provided 

 with it*." 



(1390.) Before we enter upon a description of the somewhat complex 

 generative system of a Snail, it will be proper to advert to one or two 

 remarkable circumstances connected with the procreation of these sin- 

 gular animals. We must first premise that every individual is herma- 

 phrodite, and moreover presents a kind of hermaphroditism of the most 

 perfect and complete description, possessing elaborately- constructed 

 male and female organs, which are distinct and separate from each 

 other ; but, nevertheless, the cooperation of two individuals is essential 

 to the mutual impregnation of both. The manner in which they copu- 

 late is not a little curious, their union being accompanied by prepara- 

 tory blandishments of a very extraordinary kind, that to a spectator 

 would seem rather like a combat between mortal foes than the tender 

 advances of two lovers. After sundry caresses between the parties, 

 during which they exhibit an animation quite foreign to them at other 

 times, one of the snails unfolds from the right side of its neck, where 

 the generative orifice is situated, a wide sacculus, which, by becoming 

 everted, displays a sharp dagger- like spiculum or dart attached to its 

 walls. Having bared this singular weapon, it endeavours, if possible, 

 to strike it into some exposed part of the body of its paramour, who, on 

 the other hand, uses every precaution to avoid the blow, by speedily 

 retreating into its shell. But, at length having received the love- 

 inspiring wound, the smitten snail prepares to retaliate, and in turn uses 

 every effort to puncture its assailant in a similar manner. The darts 

 are generally broken off in this encounter, and either fall to the ground, 

 or else remain fixed in the wounds they have inflicted. After these 

 preparatory stimulations, the snails proceed to more effective advances. 

 The sac of the dart is withdrawn into the body, and another sacculus is 

 by a like process protruded from the common generative aperture. Upon 

 the last-named organ two orifices are seen, one of which leads to the 

 female generative system, while from the other a long and whip-like 

 penis is slowly unfolded, being gradually everted like the finger of a 

 glove, until it attains the length of an inch or more ; and then each of 

 the two snails, by inserting its penis into the female aperture of the 

 other, impregnates its partner, and is itself impregnated at the same 

 time. Such is the peculiar manner in which the amours of snails are 

 conducted. Let us now examine the internal viscera connected with the 

 process. 



(1391.) The sac of the dart first requires our attention. This viscus, 

 * Edinb. Journ. of Nat. and Geogr. Science, iii. p. 325. 



