36 ESSAY ON CLASSIFICATION 



the limits of the genera, and a few cases in which it is actually con- 

 fined to the 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 circumstance which shows 

 that when called into existence in such an association, these various 

 animals and plants were respectively adapted, with all the peculiari- 

 ties 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 con- 

 trary would really amount to asserting that wherever a variety of or- 

 ganized beings live together, no matter how great their diversity, 

 the physical agents prevailing there must have in their combined ac- 

 tion the power of producing such a diversity of structures as exists in 

 animals, notwithstanding the close connection in which these ani- 

 mals stand to them, or to work out an intimate relation to them- 

 selves in beings, the essential characteristics of which have no refer- 

 ence to their nature. In other words, in all these animals and plants 

 there is one side of their organization which has an immediate refer- 

 ence to the elements in which they live, and another which has no 

 such connection, and yet it is precisely this part of the structure of 

 animals and plants 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 ob- 

 jection that the elements in which animals and plants live (and un- 

 der this expression I mean to include all that is commonly called 

 physical agents, physical causes, etc.) cannot in any way be considered 

 as the cause of their existence. 



If the naturalists of past centuries have failed to improve their 

 systems of Zoology by introducing considerations derived from the 



^ In the study of the geographical distribution of animals and plants and their re- 

 lations to the conditions under which they live, too little importance is attached to 

 the circumstance that representations of the most diversified types are everywhere 

 found associated, within limited areas, under identical conditions of existence. These 

 combinations of numerous and most heterogeneous types, under all possible variations 

 of climatic influences, severally circumscribed within the narrowest limits, seems to 

 me to present the most insuperable objection to the supposition that the organized 

 beings, so combined, could in any way have originated spontaneously by the working 

 of any natural law. 



