ORGANS OP SMELL. 201 



gold snuff-box, for a short time, and then the box be 

 cleansed with soap and water, still it will retain the odor 

 of musk for years. 



The sense of smell is conveyed to the brain by a pair 

 of nerves, called the olfactory, which are spread on the 

 sides of the nostrils. 



Dr. Magendie says that the olfactory apparatus ought 

 to be described as a sort of sieve, placed in the passage 

 of the air, as it is introduced into the chest, and intended 

 to stop every foreign body that may be mixed with the 

 air, particularly the odors. 



In all the terrestrial animals the cavity of the nostrils 

 is divided into two parts by a vertical partition, the 

 whole interior being lined by a soft membrane, called 

 the schneiderian or pituitary membrane. This is con- 

 stantly kept moist by glands which secrete a fluid for 

 that purpose. 



This membrane is well supplied with blood vessels, 

 and with nerves from the olfactary pair. These nerves 

 in carnivorous animals are much larger, than in those 

 that live on vegetables. 



In most animals the bony structure of this part of the 

 skull is exceedingly intricate, and therefore cannot be 

 described to the understandings of those who have no 

 previous knowledge of anatomy. We must consequent- 

 ly refer those of our readers who wish to examine this 

 point more particularly, to some treatise on that subject. 

 The best way, however, is to take the head of some 

 quadruped, and with a fine saw, divide the parts both 

 transversely- and longitudinally. Such an examination, 

 assisted by a good description, will give the general stu- 

 dent all the information he may want on this subject in a 

 few hours. 



Olfactory nerves of the Duck. We give a single lon- 

 gitudinal figure on this subject, in which the olfactory 

 nerves are peculiarly conspicuous, both from their size 

 and mode of distribution. This is the upper mandible of a 



