IV.] INTRODUCTION. Ixxi 



of slugs and snails in gardens. The application of lime 

 has only a temporary effect ; and it may do as much 

 harm as good by overstimulating the chemical ingredients 

 of some soils. An ingenious method has been proposed 

 for protecting flowers by surrounding the bed with cop- 

 per and zinc wire, the former being outermost. The 

 wire should be laid on the ground and kept clear of 

 dirt, or fixed in such a way that the snails and slugs 

 must crawl over it to reach the flower-bed. In attempt- 

 ing to do this, they receive an electric shock, and they find 

 the sensation so uncomfortable or unusual, that they 

 never venture to transgress the forbidden boundary. Pro- 

 fessor Wheatstone assures me that he has no doubt such 

 a galvanic battery, or "slug-shocker," would answer the 

 desired purpose. 



Study of Conchology. As Wordsworth nobly says, 



" Know that pride, 



Howe'er disguised in its own majesty, 



Is littleness ; that he who feels contempt 



For any living thing, hath faculties 



Which he has never used ; that thought with him 



Is in its infancy." 



Besides the interest which belongs to the study of any 

 branch of Natural History for its own sake, Conchology 

 has other claims on our attention in consequence of its 

 important relation to Geology. The first consideration 

 leads us to admire (if our limited sphere of mental vision 

 does not enable us to fully comprehend) the infinite 

 wisdom, harmony, and variety of that wonderful scheme 

 of creation which connects us with all our fellow-creatures 

 in one common bond of sympathy ; and it also teaches 

 us a lesson of humility, by showing that all our phy- 

 sical, and perhaps even our mental, faculties are shared 

 with us by other animals, far indeed inferior to us in 

 organization, but equally enjoying the prescient and 



