AND IHYSIOLOGY. 



415 



may be expanded over as great a surface as possible. The 

 cavities in the bones of the face and skull in these animals, as 

 well as also the Horse and Deer, are very much developed, 

 and all the mammalia, except the Whale tribe, are supplied 

 with a turbinal bone, the cavities of which are lined by a 

 membrane which greatly aids in the sense of smell. The 

 sense of smell is also greatly developed in the timid grazing 

 animals, so that they may in this way receive notice of the 

 approach of their enemies and escape. For most quadrupeds 

 give off a strong odor from their bodies, in the exhalations of 

 the skin. 



768. Smell in Birds— A Nasal G 1 a n d .— Birds possess 

 turbinal bones and a large nasal cavity, but it is doubted 

 whether much of the power of discerning their prey de- 

 pends on this sense, or whether it does not entirely depend 

 on vision. For the olfactory nerve merely ramifies upon 

 a part of the nasal cavity, the remaining portion being sup- 

 plied with branches from the fifth pair. There is, how- 

 ever, a peculiar gland called the nasal, which serves the pur- 

 pose of lubricating the pituitary (or mucous) membrane, which 

 is probably necessary from the fact that so much air is con- 

 stantly passing over the nostrils that the membrane would 

 otherwise become dry and thus impair the sense of smell. 



769. Smell in Reptiles— Reptiles seem by their organiza- 

 tion of very simple nasal cavities, to have their sense of smell 

 feebly developed. A few only have bony or cartilaginous 

 turbinal organs, and a portion only have the cavities lined 

 by a pituitary membrane ; and from the gormandizing habits 

 of these animals, we see that the sense of smell could be of 

 but little service to them. 



770. Smell in Fishes— Fishes possess a cavity lined by a 



What bone is the whale tribe wanting in ? How is the sense of smell in grazing ani- 

 mals? 768. How well developed are the organs of smell in birds? What is probably tho. 

 case with regard to their powers of smell ? What gland is furnished to them which pop- 

 sibly aids this sense? 769. What is said of this sense among reptiles ? Is this sense of 

 any great value to them ? 



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