46 NATURAL ARRANGEMENT OF INSECTS. 



by which Nature glides from one into the other ; and 

 this change is ahnost so imperceptible, that it is nearly 

 impossible to say where one terminates and the other 

 begins. Nevertheless, in the most intricate cases, we 

 hold the distinction to be definite, and therefore ab- 

 solute. According to the predominance of characters, 

 having relation to two diflFerent groups, which an in- 

 sect exhibits, so are we to determine its relative station 

 in the scale of being. It may, indeed, sometimes hap- 

 pen, that the balance turns on almost an incalculably 

 minute excess of the preponderating quality; but even 

 that is quite sufficient to serve our purpose : on the 

 other hand, if the balance is absolutely equal, we re- 

 gard the subject as presenting that point of union which 

 connects one group to the other : each, then, is definite ; 

 for, so soon as we arrive at that point of the series 

 where its distinguishing marks disappear, we quit its 

 limits, and enter those of another. 



(41.) We may conclude this chapter by answering 

 an interrogation, which the student may fairly put to 

 us. What is an insect ? To this we would reply. Any 

 creeping thing which has jointed legs. This question, 

 which the modern changes — for we cannot call them im- 

 provements—have involved in much technical obscurity 

 (unintelligible to all but the initiated), is thus simply 

 answered, because it really and truly expresses the very 

 essence of our theory. In proportion, however, to the 

 diversity of objects contained in all aberrant groups, so 

 will be the difficulty of a precise definition. Thus, if 

 the question related to annulose animals generally, the 

 answer of — Every animal having joints to its body — 

 must be received under a few limitations ; since, in the 

 very lowest of these, as in the hair-worms, and some 

 others, no joints are to be distinguished. In respect to 

 the two typical groups, we should term the Aptera or 

 wingless the sub-typical, and the typical the true or four- 

 winged insects ; although the Diptera, which enter 

 within the confines of the Aptera, are really possessed 

 of two wings. 



