224 



HARDWICKE'S SCIENCE-GOSSIP. 



NOTES ON THE COMMON GARDEN SLUG. 



VERY few people who have cultivated a small 

 garden plot have escaped the depredations 

 .committed on their plants by that pest, the garden 

 slug (Limax flavus). By universal consent they are 

 objects to be destroyed as soon as discovered, if we 

 would preserve our plants from their ravages. 



Comparatively few, however, of its exterminators, 

 have any idea of the wonderful piece of mechanism 

 employed by this creature for procuring its food, 

 .and the following brief description may not be 



from a slug measuring two inches in length, when 

 fully extended. When first removed it bears some 

 resemblance to a split tube bent into a V-shape form ; 

 the fold of one arm, however is reversed, so that the 

 surface which is exterior in one arm becomes the 

 interior one in the other. It consists of a moderately 

 strong membrane, and, when unfolded and fully 

 expanded, measures ^ inch long by 2 2 j in breadth. 



Arranged in parallel rows, transverse to the length, 

 are the numerous teeth or denticles, with which it 

 breaks down the tissues of the plant attacked ; the 

 denticles in the object before me amount to the 



J 1 'g- '3o. — Jaw of Li/iiaxjfaviis. X 28 diams. 



<e?3£^fP3 



Fig. 131. — Top view of 

 three denticles, mid- 

 dle portion of tongue. 

 X 200 diams. 



Fig. 132. — Side view 

 of same. 



Fig. 133. — Denticle 

 near margin. X 200 

 diams. 



Fig. 129. — Tongue of Limax flavus. X 28 diameters. 



.altogether uninteresting to the general reader ; while 

 to those who take an interest in practical microscopy, 



,and are possessed of ordinary manipulative ability, 

 the procuring of the tongue is not such a very difficult 



.affair, and the trouble expended will be amply repaid 

 by the possession of an exquisitely fine object, the 

 study of which cannot fail to impress upon the mind 



-the wonderful adaptability of the organ for the 



iperformance of its function. 



The apparatus consists of two distinct parts, viz. 



the tongue, or odontophore, and the jaw. The typical 



.object from which these notes are made was taken 



enormous number of twenty-two thousand one 

 hundred. At first glance it might be thought they 

 were similar on all parts of the tongue, but a higher 

 power reveals the fact that there is variety even here, 

 those on and near the margin of the tongue being of 

 a different character to those on the central portion ; 

 the former are long and narrow, as compared with 

 the latter, and measure ^ m long by ^ m broad, while 

 the latter measure ^ long by r ] 5!j in breadth. 



The anterior portion of the tongue shows unmis- 

 takably the friction it has been subject to, the mem- 

 brane being fractured, and the denticles partly 



