CHAPTER III. 



THE METAMORPHOSES OF THE NERVOUS SYSTEM. 



Nothing can be more striking at first sight than the difference 

 between the nervous apparatus of the larva, of the bee, for instance, 

 and that of the perfect insect ; or between that of the larva of the 

 water-beetle and the mature Dytiscus. But a careful examination 

 of the anatomy of the nervous masses, and of the conducting cord 

 between them, will tend to show that there is not a perfect altera- 

 tion in their arrangement before and after metamorphosis. There 

 is great modification, but the original design never loses its im- 

 pression, through all the eccentricities of growth, upon the struc- 

 tures of the nervous system of the most elaborately-formed perfect 

 insect. We have seen that the segments of the larva become 

 apparently less numerous in the imago or perfect insect, and it has 

 been stated that the diminution of the number of these important 

 body-rings is brought about by their coalescence. Now, there is 

 a remarkable relation between the segments of the body of the 

 articulate animal and the disposition of its nervous structures, and 

 it will be noticed that as the segments coalesce, so do also por- 

 tions of those wonderful parts which enable the will to be exer- 

 cised, instinct to be made manifest, and the senses to be enjoyed. 



The nervous masses coalesce in order to become more perfect 

 in their functions ; they concentrate their influence and make the 

 insect less vegetative and more intelligent. The feeble nerves of 

 many larvse are remarkable when the activity and importance of 

 those of the perfectly developed insect are considered ; there 

 is an evident relation between the wants of the animal and its 

 gifts, and these are showered down according to that wonderful 



