CLASSIFICATION OF INSECTS. 167 



four and seven ; in other words, to contain four 

 groups, three of which shall be double groups, 

 and one single group : this circumstance has led 

 to much argument as to the superiority of the 

 particular numbers, two, four, and seven. Some 

 writers have also contended for the numbers three 

 and five.* 



618. The relative position in which the objects 

 of nature stand, has been also the subject of great 

 discussion ; some authors contending that the 

 system of nature is represented by a straight 

 line ; others, by the branches of a tree ; others, 

 by the circumference of a circle. No decision on 

 either number or position has yet been made by 

 naturalists ; indeed, it is the general opinion, 

 that no particular number or position is constant 

 in nature. 



619. The author ventured to suggest, in a 

 little essay, published some time since, that seven 

 was the predominant number ; and that, in every 

 group of seven, whether the group be large or 

 small, one of the seven is central, and the other 

 six surround it, and are each connected with it : 

 this is called the septenary system. 



620. The septenary system has not been 

 generally received ; on the contrary, it has been 

 written against with what the author thinks 



* The principal advocates of particular numbers are these : Flem- 

 ing, two ; Swainson, three ; Cuvier, four ; Mac Leay, five ; the 

 author, seven. 



