Kew : On the Pairing of Limax maximus. 



within the penis, the opening- of the vas deferens (f) becoming- 

 external. 



It will be remembered that Boch-Buschmann long ago 

 suggested that the sexual union does not here involve intro- 

 mission of the penis. This suggestion, at first sight, seems 

 improbable, and Professor Jourdain, who has discussed the 

 point, believes that copulation with intromission will be found to 

 take place in Limax maximus as in other slugs.* When we 

 glance at Fig. 5, however, and observe the small size and posi- 

 tion of the receptaculum seminis and its duct (rs), and the 

 relatively vast dimensions of the everted penis, we cannot 

 readily dismiss the suggestion of Boch-Buschmann, and I think 

 it may be said to be established that no intromission occurs. 

 This view is expressly supported by Purkyne, Baudelot, Laurent, 

 and Webb. One has to note further that no observer appears 

 to have seen anything tending to weaken it, no approach being 

 made by the penis of either animal towards the genital aperture 

 of its fellow. 



How then does the sperm — discharged from the opening of 

 the vas deferens at the extremity of the penis — find its way into 

 the duct of the receptaculum seminis? Purkyne, who says that 

 he could see the chalky white sperm through the transparent 

 walls of the intertwined penes, supposed it to be discharged 

 into the interior of the spiral, and to be forced upwards to the 

 genital apertures by the contractions and movements of the 

 organs. The observer finds support for this idea in the fact 

 that in the penes which he bound during union, sperm was found 

 in clumps on those parts of the surface of the organs which, 

 when they were intertwined, had formed the inner wall of the 

 spiral (Fig. 5, sp). Baudelot, on the other hand, arrived . at 

 a somewhat different conclusion. He found within the cavity of 

 the penis a considerable longitudinal fold. This, of course, 

 becomes external when the organ is everted, and it is supposed 

 to give rise to the ' frill ' already referred to. It serves also for 

 the formation of a longitudinal groove upon the everted organ ; 

 and this groove, Baudelot thinks, is of considerable functional 

 importance. While the penes are wound together, he says, the 

 sperm, running from their extremities, probably spreads over 

 the corresponding organ of the other animal, and is received by 

 the groove ; and, according to this view, it is when the organs 



* Jourdain, Note sur les org-anes genitaux et l'accouplement de quelques 

 Limaciens, Revue des Sciences Naturelles, VII. (1878), pp. 421-2. 



Naturalist,. 



