CLASS INSECTA. O 



giarif germinates, according to this author, four pairs of 

 nerves, and the following, two pairs each ; so that, reckoning 

 tlie eight pairs of the brain, the ten spinal bridles, which 

 may be considered as so many pairs of nerves, we have in all 

 forty-five pairs, independently of the two solitary nerves, or 

 from a dozen to fourteen more than are in the human body. 

 The two nervous cords, which, by their union, form the 

 ganglia, are tubular, and composed of two tunics, the ex- 

 terior of which presents tracheae. A medullary substance 

 fills the central canal. The excellent work of M. Herold on 

 the anatomy of the caterpillar of the large cabbage butterfly, 

 studied in its progressive growth, to its transformation into 

 the chrysalis, shews us that the nervous system and that of 

 the digestive organs undergo remarkable changes ; that the 

 nervous cords are in their origin longer and more separated, 

 an observation which favours the opinion of one of the 

 greatest zootomists of our age, Dr. Serres, on the origin and 

 development of the nervous system. We have explained 

 in the generalities common to the three classes of articulated 

 animals with articulated feet, the various sentiments of phy- 

 siologists on the seat of the senses of hearing and of smell. We 

 shall confine ourselves to adding, that, with regard to the 

 first, the small nervous ganglia situated on the forehead, of 

 w^hich we have spoken, seem to confirm the opinion of those, 

 such as Scarpa, who place the seat of this sense near the 

 origin of the antennas. In some lepidoptera, I have observed 

 two small holes situated near the eyes, and which, perhaps, 

 are auditory conduits. If, in many insects, especially those 

 which have filiform or setaceous and long antennae, these or- 

 gans answer the purpose of tact, it appears difficult to give 

 a reason for the extraordinary development which they ac- 

 quire in certain families, and more particularly in the males, if 

 Ave do not admit that they are then the seat of smell. Per- 

 haps, also, in relation to taste, the palpi play in some cases, as 



