82 ARRANGEMENT OF ANIMALS. 



reticular contractile tissue, with fluids in its interstices, 

 the general essence of their structure ; substances easily 

 convertible into the state of liquid or gas, and combinations 

 readily changing, the basis of their chemical composition. — 

 Fixed forms, perpetuated by generation, distinguish their 

 species, determine the combination of secondary functions 

 peculiar to each, and assign to them their respective situa- 

 tions in the system of the universe. 



After forming this general notion of living beings, we 

 proceed to examine the animal kingdom in detail. The 

 first glance discovers to us an infinite variety of forms ; 

 diversities so numerous, that the attempt to observe and 

 register the whole seems almost hopeless. We find, how- 

 ever, that tliese forms, at first view so infinitely various, 

 admit of being classed together — of being formed into 

 groups, each of which is distinguished by certain essential 

 characters. In the latter, all the animals comprehended in 

 each group agree; while they difl^er from each other in 

 particulars of minor importance. 



I have already mentioned, that a fixed external form be- 

 longs to each animal, and that it is continued by genera- 

 tion. Certain forms, the same as those existing in the world 

 at the present moment, have existed from time immemorial. 

 Such, at least, is the result of the separate and combined 

 proofs furnished by our own observation and experience 

 respecting the laws of the animal kingdom, by the voice of 

 tradition and of history, by the remains of antiquity, and 

 by every kind of collateral evidence. 



All the animals belonging to one of these forms con- 

 stitute what zoologists call a species. This resemblance 

 must not be understood in a rigorous sense; for every 

 being has its individual characters, of size, figure, colour, 

 proportions. In this sense, the character of variety is 

 stamped on all Nature's works. She has made it a fun- 

 damental law, that no two of her productions shall be 

 exactly alike ; and this law is invariably observed through 

 the whole creation. Each tree, each flower, each leaf, ex- 

 emplifies it ; every animal has its individual character ; each 



