404 THE SENSORIAL FUNCTIONS. 



deed, distinguishes more accurately vegetable 

 odours than those proceeding from animal sub- 

 stances ; while the reverse is observed with re- 

 gard to quadrupeds whose habits are decidedly 

 carnivorous. A dog, for instance, is regardless of 

 the odour of a rose or violet ; and probably, as 

 he derives from them no pleasure, is unable to 

 discriminate the one from the other. Preda- 

 cious animals, as Sir B. Harwood observes, 

 require both larger olfactory nerves, and a more 

 extensive surface for their distribution, than the 

 vegetable eaters. The food of the latter is ge- 

 nerally near at hand ; and as they have occasion 

 only to select the wholesome from the noxious 

 plants, their olfactory organs are constructed for 

 the purpose of arresting the effluvia of odorous 

 substances immediately as they arise. The former 

 are often under the necessity of discovering the 

 lurking places of their prey at a considerable 

 distance, and are therefore more sensible to the 

 weak impressions of particles widely diffused 

 through the surrounding medium, or slightly ad- 

 hering to those bodies, with which the object of 

 their pursuit may have come into contact. 



The olfactory bones of birds are constructed 

 very much on the model of the spiral bones of 

 herbivorous quadrupeds, and vary but little in 

 the different species. Fig. 386 exhibits their 

 appearance in the Turkey : but the size of the 

 olfactory nerves of birds of prey greatly exceeds 



