PAET I. 



PHYSICAL INVESTIGATION. 



THE notion of species is founded upon the fact that the typical 

 similarity of natural objects is preserved throughout all their 

 changes. Between the inorganic and organic kingdoms of 

 nature, there obtains in this respect only this difference : that 

 the sphere of action is larger or more manifest in the organic 

 world, the natural laws leaving a wide margin for the produc- 

 tion of individual varieties, and further that the preservation of 

 types can only be effected by the propagation of individuals 

 belonging to them. Apart from this, the signification of the 

 term species applies equally to organic and inorganic objects ; 

 it designates the constancy of the assemblage of characters oc- 

 curring, regularly combined, in nature. 



Without entering into any details with regard to the abuse 

 made of this term in philosophy, it may be sufficient to observe, 

 that species are neither mere subjective abstractions formed 

 only to classify the innumerable natural objects, nor are they 

 exemplars, which, as active principles, form the foundation of 

 all natural objects. They are, in fact, nothing else than empi- 

 rical laws of natural production ; for the constant coincidence 

 of similar characters must have as its fundamental cause a cor- 

 responding constant assemblage of natural conditions. 



So long, therefore, as by the term species nothing more is desig- 

 nated than the typical similarity of natural phenomena, the regu- 

 larly recurring complex of characters, and the regular recurrence 



