458 ON THE TRIBES OF MANDIBULATA. 



disciples have, in pursuance I suppose of an expression in 

 the Classes Plantarum, been always called Natural Orders, 

 he himself with admirable caution also named fragments 

 of a natural method ; by this implying that the intervals 

 which separate them are not natural, but the consequences 

 of our ignorance of species. Hence we have the observa- 

 tion, " Plantid omnes iitrinque affinitatem monstrant uti 

 territorium in Mappa Geographicd" which, to be sure, is 

 sufficient evidence of his never having suspected much re- 

 gularity to exist in the creation. Still more to the purpose 

 therefore is the remark which follows, " Defect us nondum 

 detectorum in causa fuit quod methodus naturalis deficiat, 

 quam plurium cognitio perficiet; natura enim non facit 

 saltus." 



Now, although no where can I find it positively express- 

 ed, and although the Linnsean definition of genera appears 

 even in opposition to it, I conceive this idea, that absolute 

 divisions do not exist in nature, to lead directly to that 

 which is still more important, namely, that the only pro- 

 bability of o\xx ever understanding the great scheme of 

 the creation must depend on studying the method in which 

 the organs and properties of natural beings vary. All 

 true knowledge of Natural History hinges on this — Ordinis 

 hac virtus erit et venus. 



