in Organized Beings. 95 



From the structure of the wings, and then- coiTespondence 

 with the acknowledged respiratory organs of aquatic insects, 

 we might infer their nature with considerable probability ; we 

 shall next briefly trace their connections in search of the same 

 object. If we cast a glance at the gradual development of the 

 organs of locomotion formed by appendices to the trunk in as- 

 cending the scale in the articulata, we shall see their first ap- 

 pearance in the setse of the earth-worm, and the filamentous 

 tufts of the nereis, the latter serving both as branchiae and as 

 instruments of progression. In the higher annelides, one of 

 the setae of each tuft is more developed than the rest, forming 

 a long tubular-jointed appendix to each segment, which is evi- 

 dently the rudiment of the leg perfected in the myriapodes. 

 The twelve segments forming the body of the caterpillar 

 (which may be regarded as for the time an annelide), are each 

 provided with a pair of legs ;* and these are sufficient to exe- 

 cute the movements which the aniinal requires in this stage of 

 its existence, when the whole energies seem as it were concen- 

 trated on the nutritive system. When the adult insect emerges 

 from the chrysalis, however, after losing for a time all appear- 

 ance of external members, it is found that the nine posterior 

 segments forming the abdomen are entirely destitute of appen- 

 dages, whilst the three thoracic segments are provided not only 

 with three pairs of legs, but with two pairs of wings attached 

 to the second and third segments. If these wings had taken 

 the place of the legs which disappear during the metamorphosis, 

 there might have been some ground for considering them ana- 

 logous organs ; but if we contrast their position on segments 

 which retain their legs ^vith that of the branchial tufts of the 

 annelides, it must, I think, be acknowledged that we thus de- 

 rive from their connections another strong argument in favour 

 of the view I am advocating. 



It remains for us now to consider their development ; and 

 though I regard this as an important link in the chain of evi- 

 dence, I cannot see that it affords more than a corroboi'ative 

 pi'oof, or that we should be entitled to take up such a bold po- 

 sition witliout a firmer foundation. After the third moult, the 



" I am of course speaking in tliis,as in other cases, of the regularity or typical 

 form. 



