in Natural History. 2J5 



used by naturalists, has a more confined signification than the 

 same word when employed in scholastic language. We have 

 agreed that a species shall be that distinct form originally so 

 created, and producing by certain laws of generation others 

 like itself: whereas all that logicians have meant, is a number 

 of objects bearing a certain resemblance to one another, and 

 on that account denominated by a single appellation, which 

 may be employed to express any one of them. This term is 

 the creature of art, to help us up the first step of generaliza- 

 tion. By its assistance we propose to reason upon all the in- 

 dividuals conforming to the law we have laid down, as safely as 

 we can do of any one of them. There is this inconvenience at- 

 tending the use of it by naturalists, that it assumes as a fact, that 

 which in the present state of science is in many cases a fit sub- 

 ject of inquiry; namely, that species, according to our definition, 

 do exist throughout nature. It is too convenient a term to be 

 dispensed with, even as an assumption ; only care should be 

 taken that we do not accept the abstract term for the fact. 



It might, for instance, be proposed as a legitimate question, 

 whether the species of some familiar genera, such as Rosa, 

 Rubus, Saxifraga, do not run into one another by impercepti- 

 ble shades, unappreciable by human sense, in the same man- 

 ner as certain genera melt and intermingle their characters, so 

 as to render it impossible to circumscribe them. Indeed, the 

 extent to which species-making has been carried in modern 

 times, almost leads to this conclusion. Visible and palpable 

 distinctions are in many cases no longer relied on ; and there 

 are many acute naturalists, who, without bringing the subject 

 to the test of experiment, are content to rely on those empi- 

 rical characters, which can only be perceived by long and fa- 

 miliar experience, and cannot be described by words. The 

 truth is, that all sensible objects have characters which leave 

 impressions upon the mind, without our being capable of em- 

 bodying them in language. We are all aware of this when 

 we speak of tastes, and tints, and the countenances of our 

 friends. Every-body perceives them, yet nobody can com- 

 municate to his neighbour his perception of their differences. 

 Thus botanists speak of certain species of plants differing in 

 appearance, habit, touch, &c. ; by which they often mean that 

 they have some indescribable peculiarities about them, which 

 point them out to the practised observer as distinct. A great 

 number of such species may be detected in every modern Flora 

 of a well investigated country ; but whether they deserve to be 

 ranked among those which are capable of definition, is a ques- 

 tion of great doubt : — that the practice is an inconvenience, 

 none will deny ; and if it be much longer continued, will in- 

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