SMELL. 



357 



tory nerves. The relative magnitude of these nerves 

 is much greater in carnivorous quadrupeds than in 

 those which subsist on vegetable food. In quadru- 

 peds, as well as in man, these nerves, in their course 

 towards the brain, are not collected into a single 

 trunk, but compose a great number of filaments, 

 which pass separately through minute perforations 

 in a plate of bone, (called the ethmoid hone), before 

 they enter into the cavity of the skull, and join that 

 part of the cerebral substance with which they are 

 ultimately connected. In every class of vertebrated 

 animals, it has been found that the internal surface 

 of this membrane is furnished with cilia, in great 

 numbers, producing the usual currents in the tluid 

 in contact with them. 



The surface of the membrane which receives the 

 impressions from odorous effluvia, is considerably 

 increased by several thin plates of bone, which pro- 

 ject into the cavity of the nostrils, and are called 



the turbinated hones. These are delineated at t, r, 

 in Fig. 382, as they appear in a vertical and longi- 



