448 ON THE TRIBES 



called the recurrent. This supplies the coats of the sto- 

 mach and intestinal canal. In the perfect insect, on the 

 other hand, the double knotted longitudinal cord of the An- 

 nulosa is very distinct, and the animal would seem to have 

 changed a spinal marrow for a sympathetic nerve. 



Similar changes to a greater or less amount take place 

 in other insects. Nor does the system of nutrition undergo 

 a less extraordinary transformation by metamorphosis ; 

 for, to take again the larva of the said Oryctes, we find 

 that not only the structure of its mouth, but the whole 

 form and disposition of its intestinal canal are undiscernible 

 in the perfect insect. The same circumstance holds good 

 in the Frog, which in its perfect state has the short narrow 

 intestine proper for an animal destined by nature to feed 

 on insects ; whereas while a tadpole, it possessed a long 

 spiral intestine, such as better suited its herbivorous dis- 

 position. 



If, finally, the alterations developed by metamorphosis 

 in the organs of respiration and generation be taken into 

 view, we must be absolutely convinced that the Naturalist 

 cannot neglect the particulars of ecdysis in his arrangement 

 of the Annulosa, without resorting to artificial principles 

 in their stead. From the study of Metamorphosis, indeed, 

 we may be said to learn every circumstance of the lives of 

 such animals as are guided solely by instinct; and just as 

 a knowledge of the whole life of an insect must make us 

 better acquainted with its nature than a mere description 

 of one of its forms, in the same proportion ought Meta- 

 morphosis to outweigh every other principle of arrange- 

 ment. 



There is perhaps no maxim in the Philosophia Entomo- 

 logica more sound or more worthy of notice than the follow- 



