CHAP. IX.] AND OF BIRDS. 137 



Bird, by that of those with which we are ourselves familiar. 

 In such animals many visceral impressions may be 

 decidedly attended by more of conscious accompaniment 

 than those which we experience, and they may enter in a 

 much larger proportion into the web of sensory impressions 

 constituting the basis of the conscious life of such creatures. 

 Professor Owen truly says of Fishes that, " the appetite 

 for food appears to be their predominant desire, and pro- 

 viding for its gratification to form their chief occupation." 

 Certain it is, that when prompted by different visceral 

 states, animals may show an extraordinary amount of 

 sensorial activity and power of executing related muscular 

 movements. The sensorial endowments of the Shark, 

 of the Python, or of the Vulture, are, when these 

 creatures are under the influence of hunger, exalted to 

 ^he highest degree ; so that at such times either of them 

 may become keenly sensitive to odours, sounds or sights 

 which, had they been in a state of satiety, might have 

 passed wholly unheeded. Similar differences also exist 

 between the degree of sensorial activity of animals 

 swayed by sexual desires, and those in whom such feelings 

 are quiescent. These tw r o classes of visceral promptings 

 largely instigate and dominate the brain activit}^ of all 

 lower animals, and when the related needs or desires 

 no longer exist, and no longer rouse the creature's senso- 

 rial activity, sleep is apt to come, as with a veil, and sever 

 for a time the correspondence between the organism and 

 the outer world. 



