Ill) CLASS AVES. 



This extreme vivacity, common to the majority of birds, ren- 

 ders them less capable of education than other more tranquil 

 animals, and produces, in this respect, the same effect as its 

 opposite quality, stupidity. For though they are well orga- 

 nized for the purposes of learning, their boiling impetuosity, 

 the perpetual variety of their motions and sensations, hinder 

 them from fixing their attention, so- that ideas shall be per- 

 manently imprinted in their sensorium. Still they appear to 

 imagine much in the variety of their operations and migra- 

 tions ; but this appears to be the result of instinctive feeling, 

 rather than of intelligence. They have, generally speaking, 

 but slight glances of things, which are easily effaced by 

 time. They experience only fugitive impressions, which are 

 speedily replaced by others equally fugitive. They feel, 

 in fact, more than conceive. An attention, a steady and 

 reflective character is necessary to penetrate into the know- 

 ledge of things. Thus w^e find the elephant, whose gravity 

 and reflexion are so remarkable, is also one of the most 

 intelligent of animals. Parrots, which are in general less tur- 

 bulent than other birds, are also more susceptible of instruc- 

 tion ; and if we succeed in teaching Canary birds, goldfinches, 

 linnets, &c., it is only by keeping them imprisoned, and con- 

 straining them perpetually to attend and reflect. It has been 

 even observed that birds become blind receive instruction with 

 greater facility than otners, because their attention is less dis- 

 tracted. This observation has given rise to the atrociously- 

 cruel practice of bird-fanciers in burning out the eyes of 

 nightingales and other birds which they keep in cages. 



The articulation of the head by a single round condyle is 

 remarkable, as it enables the bird to turn the front of the head 

 full half way round, which no other vertebrated animal can do. 



The brain of this class is distinguished from that of the 

 mammalia by presenting six visible masses. These are the 

 two hemispheres, the two optic beds, the cerebellum, the me- 

 dulla oblongata. The two first are without circumvolutions, 

 and there is no corpus callosum, or septum lucidum ; but the 



