170 HISTORY OF BRITISH ZOOPHYTES. 



be carefully observed without a conception the most exalted 

 of the fertility of the Creating Mind, and the richness of 

 the creation. Evident as was the fact to Lucretius, it is 

 still more open to our observation : 



" Thus Nature varies : man and brutal beast, 

 And herbage gay, and scaly fishes mute, 

 And all the tribes of heaven o'er many a sea, 

 Through many a grove that wing, or urge their song 

 Near many a hank or fountain, lake or rill ; 

 Search where thou wilt, each differs in his kind, 

 In form and figure differs." 



Genus XV. HYDRA, Linnaus. 



Gen. Char. Polypes locomotive, single, naked, gelatinous, 

 subcylindrical, but very contractile, and mutable in form ; the 

 mouth encircled with a single series of granulous filiform ten- 

 tacula. Dr. Johnston. 



Fresh-water Hydra are so interesting a tribe of Zoo- 

 phytes, and the properties of which they are possessed are 

 so extraordinary, and have attracted so much attention, that 

 we think it may be acceptable to our young naturalists if we 

 give a brief history of the discoveries made respecting them. 

 We are the more disposed to do so, as through the kindness of 

 my excellent friend Mr. Gourlie, of Glasgow, I have at present 

 in my possession a copy in the original of M. Trembley's 



