138 



THE AMERICAN MONTHLY 



[May, 



Epidermis, 

 Dermis. 



iSubmucous 



simple vertical vessels, but are in the form of an oval 

 cluster. These vessels really underlie the cells of the 

 epidermis which receive blood from the capillaries by 

 diffusion from the spaces beneath them. This of course 

 renders it easier for the lower layers of this structure to 

 receive blood and the cells in the upper levels are at a 

 disadvantage in this respect. The consequence is that 

 they die, but not until after they have secreted a horny 

 material allied to the chitine of the insect skeleton. This 

 makes the cells extremely durable and thus enables them 

 to endure the conditions that are placed on them by their 



exposed situation. Living 

 delicate cells exposed on the 

 tongue's surface to such 

 changes as for instance 

 from a dish of ice cream 

 to a cup of boiling coffee 

 would probably give up 

 the struggle for life in com- 

 plete despair. The outer 

 surface of the tongue is cov- 

 ered with these dead cells, 

 many layers deep, they are 

 not in the form of a flat 

 surface as in the oesophagus, but are, in the cat and 

 in all the carnivora, in the form of sharp-pointed ele- 

 vations, placed so as to point backward. These "filiform 

 papillfe " are of use to the cats in the manner of a 

 file rasping portions of the meat which constitutes their 

 diet from the bones on which it grows. In the case of 

 the lion these papillsB are so stout and strong that a sin- 

 gle lick of the creature's tongue across the back of a per- 

 sons hand would drag away with it all the skin down to 

 the bare bones. In the tongue of the cat they can be 

 also clearly seen. In the human tongue similar papillae 

 are present but they lack the sharply pointed shape of 

 tlie carnivore being flattened down on top. In all cases 



Verticul soctiou of the tongue of a cat injected. 



