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 bank or fountain, lake or rill; 
Search where thou wilt, each differs in his kind, 
In form and figure differs.” 
Genus XV. HYDRA, Linnaeus. 
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 Hydre 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 
