72 INTllODUCTION. 



able to refer to the works treating of American species, 

 so that he may ascertain whether his results have not 

 been anticipated bj others. And, if he would be worthy 

 of entire confidence, he must not confine his observation 

 to the cabinet. One who knows species only as they 

 appear in his own drawers, can have but an imperfect 

 idea of the innumerable deviations, from every type, 

 that nature permits. Specimens in cabinets are usually 

 selected for their size, beauty, and perfection, or for 

 some remarkable peculiarity about them, — those whose 

 characters are strong and well defined, being always 

 preferred, while the intermediate forms, a thousand 

 times more numerous than the others, but presenting 

 nothing notable, are neglected. The tendency to order 

 and classification, which the study of Natural History 

 creates, induces the in-door collector to separate and 

 arrange his specimens according to their resemblances. 

 With Ms materials he finds that distinctions are easily 

 established, that the bounds of species and varieties are 

 well defined, and that groups are marked by determinate 

 and fixed characters. The limits of each division seem to 

 him to be constant and not to encroach upon each other. 

 As it is in his cabinet, so he supposes it to be in nature* 

 He accordingly speculates, refines, and generalizes, and 

 ends by estabhshing a system wliich, because consistent 

 with his own experience, he thinks equally supported 

 throughout. When the same person changes the scene 

 of his observation from his own cabinet to the field and 

 the forest, and becomes acquainted with numerous 



