BINARY SYSTEMS. l3 



(250.) Binary or dichotomous systems, although re- 

 gulated by a principle, are among the most artificial 

 arrangements that have been ever invented. This great 

 principle upon which the advocates of such tables insist, 

 simply consists in arranging animals according to their 

 positive and negative characters ; as, for instance, birds with 

 perfect wings, and, secondly, birds with imperfect wings ; 

 and so on. Now this mode of arrangement is, perhaps, 

 the most simple, and the most easy of comprehension, 

 of any that has been devised; and was, therefore, the 

 earliest in use. It likewise seems to offer a ready clue 

 to the discovery of any particular species or genus, be- 

 cause the student has no occasion to look beyond the 

 table before him : he need not trouble himself about 

 affinities or analogies, for he has merely to see what 

 particular character his specimen has, and what it has not. 

 When, therefore, his object is either to ascertain the 

 recorded name of a species, or whether it be described 

 or undescribed, he will often find this sort of catalogue 

 useful. But the misfortune of the binary methods of 

 arrangement is this, that they may be multiplied ad 

 libitum. As their advocates profess not to pursue any 

 one principle in the selection of their characters, it fol- 

 lows that we may have a hundred different binary sys- 

 tems, each good in its way, but each different from the 

 other. One entomologist may choose to divide all in- 

 sects into such as have wings, and, secondly, such as 

 have none. Another, looking to the manner of feeding, 

 may make his two groups depend upon one having jaws, 

 the other none. A third, considering metamorphosis 

 as the corner-stone of his system, may divide all insects 

 into such as undergo this transformation, and such as 

 do not. Hence, it follows, that every one may form a 

 binary system of his own, provided he closely attends 

 to, and " possesses distinct conceptions on, positive and 

 negative characters ;" the only requisite, as its advocates 

 affirm, for this mode of arrangement. As for preserving 

 the natural affinities of groups, it is by no means ne- 

 cessary to the systems in question that any regard should 







