on the Wing- Rays of Insects. 227 



customed to smile at the transcendental hypothesis of Oken, to 

 regard his great peculiarities, the substitution of hypotheses for 

 truths, of verbs for nouns, that we agree in discarding this idea, 

 which, however, divested of two errors, first, the mistaking of an 

 analogy for an homology, and secondly, the mistaking of an active 

 for an apathetic function, evidently indicates an acute percep- 

 tion of facts, which however admit of an explanation totally 

 different. 



The nerve hypothesis, although by far the most popular, has 

 never been advocated with an earnestness displaying any strong 

 belief in its truth : its great reconnnendation appears to be con- 

 veyed in a name, given almost at haphazard, yet, strange to say, 

 universally received. Kirby and Spence recommend the substi- 

 tution of the word " nervure " instead of nerve, and other authors 

 have used the terms " nervelet," " nervule," " nervation " and 

 "neuration"; yet I am unaware of a single attempt to show that 

 these rays are in any respect organs of sensation ; indeed, no En- 

 tomologist will maintain that they are so ; and if the word nerve 

 is objectionable because of its untruth, then are the endearing 

 diminutives, or indeed any terms conveying the same untruthful 

 idea, objectionable also ; for it is impossible to disconnect such 

 terms from the idea of a function of feeling. 



The vein hypothesis is the last and most fashionable ; it has 

 well nigh driven the nerve hypothesis out of the field ; and is 

 adopted in this country by such eminent Entomologists as Haliday, 

 Walker, Stainton and Westwood ; the last-named of whom has 

 said, in his introductory observations to Hewitsoii and Doubleday's 

 Genera of Diurnal Lepidoptera, that, now these rays are ]n'oved by 

 physiological investigation to be veins, they ought to be so called : 

 but I hesitate to accept the premises, because I deny that a single 

 ol)servation has ever been made that can warrant such a con- 

 clusion. 



There are two modes of deducing conclusions from phenomena 

 which nature reveals to our senses, and thus makes manifest to 

 our understandings : first, by tracing the source of acts ; secondly, 

 by learning the object of structure. I am not confident that either 

 of these modes aflbrds positive, but both of them afford presump- 

 tive, evidence in favour of my conclusion, which, in addition to the 

 support thus deiived from opposite sources, receives additional 

 strength from the exactness with which acts and structure appear 

 to harmonize. But it must be borne in mind that man cannot 

 reason conclusively on the functions of a structure referrible to a 

 type essentially differing from that on which his own body i« 



Q 2 



