280 SNAILS AND SLUGS 



up-to-dateness. No doubt the explanation is partly found 

 in the keen sense of smell which all molluscs are known 

 to possess. The art of slime-spinning has been inherited 

 as a means of making short cuts; the sense of smell, 

 enjoyed in a degree which we, with our grosser faculties, 

 can scarcely realise, acts as a clue to the direction in 

 which the short cut is to be made, and the sense of 

 direction Zeno held to be slight proof of intelligence. 

 'You fool,' said he to Euclid, 'why devote columns of 

 manuscript to proving that two sides of a triangle are 

 greater than the third. Any ass knows that without in- 

 struction. Tie a bundle of hay in the corner of a court, 

 and see whether the beast will not make straight for it, 

 instead of moving round two sides of the square ! ' 



It must be confessed that, whatever be the intellectual 

 quaUties of molluscs, they exhibit no trace of conscience 

 or moral sense. The common black fellow (Arion ater), 

 which appears everywhere in numbers after a shower, is 

 professedly vegetarian, but greedily devours any carrion 

 he comes across, and cannot be trusted to keep his radula, 

 or rasping jaw, off the bodies of his weaker brethren. 

 Dr. Grey almost failed to find anything destructible 

 which Arion would not eat; it devoured newspapers 

 greedily, the bodies of five diiferent species of slugs, 

 and Pears's soap. But the last-named article was con- 

 sumed without gusto, evidently under protest against 

 the abnormal flavour, and without any intention of giv- 

 ing it an advertisement. 



