Chap. I. GEOGRAnilCAL RANGE OF ANIMALS. 33 



not absolutely, as in some the orders only, or the families only are thus closely 

 related to the elements; there are even natural groups, in which this connection is 

 not manifested beyond the limits of the genera, and a few cases in which it is actually 

 conhned to tlie species. Yet, in every degree of these connections, we find that upon 

 every spot of the globe, it extends simultaneously to the representatives of different 

 classes and even of different branches of the animal and vegetable kingdoms ; a circum- 

 stance which shows that when called into existence, in such an association, these vari- 

 ous animals and plants were respectively adapted with all the peculiarities of their 

 kingdom, those of their class, those of their order, those of their genus, and those of 

 their species, to the home assigned to them, and therefore, not produced by the nature 

 of the place, or of the element, or any other physical condition. To maintain the 

 contrary, Avould really amount to asserting that wherever a variety of organized 

 beings live together, no matter how great their diversity, the physical agents prevail- 

 ing there, must have in their combined action, the power of producing such a 

 diversity of structures as exists in animals, notwithstanding the close connection in 

 which these animals stand to them, or to work out an intimate relation to them- 

 selves in beings, the essential characteristics of which, have no reference to their 

 nature. In other words, in all these animals and plants, there is one side of their 

 organization which has an immediate reference to the elements in which tbey live, 

 and another which has no such connection, and yet it is precisely this part of the 

 structure of animals and i)lants, which has no direct bearing upon the conditions in 

 which they are placed in nature, which constitutes their essential, their typical 

 character. This proves beyond the possibility of an olyection, that the elements in 

 which animals and plants live (and under this expression I mean to include all that 

 is commonly called physical agents, physical causes, etc.,) cannot in any way be con- 

 sidered as the cause of their existence. 



If the naturalists of past centuries have failed to imj^rove their systems of Zoology 

 by introducing considerations derived from the habitat of animals, it is chiefly because 

 they have taken this habitat as the foundation of their primary divisions ; but 

 reduced to its proper limits, the study of the connection between the structure and 

 the natural home of animals cannot fail to lead to interesting results, among which, 

 the growing conviction that these relations are not produced by phvsical agents, 

 but determined in the plan ordained from the beginning, Avill not be the least 

 important 



The unequal limitation of groups of a different value, upon the surface of the 

 earth, pioduces the most diversified combinations possible, when we consider the 

 mode of association of different families of animals and plants in different parts of 

 the world. These combinations are so regulated that everj' natural province lias a 

 character of its own, as far as its animals and plants are concerned, and such natural 



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