306 



ANIMAL LIFE 



FIG. 343. Sensory nerve ter- 

 mination in the mesentery of 

 the cat. From Davison's 

 " Mammalian Anatomy." 



lower vertebrates, but numerous 

 experiments have been made with 

 insects. Most caterpillars will re- 

 fuse all but one or two kinds of 

 leaves, and many bugs will die of 

 starvation rather than suck the 

 juice of plants to which they are 

 not accustomed. When the sugar 

 upon which bees are feeding is ex- 

 changed for pulverized alum, the 

 insects splutter and spit in a way 

 that indicates a well-developed 

 sense of taste. Ants love sugar, 

 but if strychnine is mixed with it 



they reject the food at once. The organs of taste in 



insects are minute pits containing fine 



taste hairs. They are present in the 



maxilla and tongue of ants, bees, and 



wasps, and on the proboscis of the 



flies. 

 The sense of smell varies widely in 



efficiency among the different animals. 



It is well developed in most terrestrial 



mammals, but more or less rudimen- 

 tary in the other classes of vertebrates. 



A dog familiar with the smell of 



his master can track him through a 



crowded street with the same ease 



that we can follow a man by sight. A 



deer will discern the presence of man 



a half mile distant to windward. It 



FIG. 344. Head of the 

 bumblebee, a, anten- 

 na ; g, glossa or tongue 

 used in licking the nec- 

 tar from flowers ; l t 

 paraglossa; m, maxil- 

 lae. Photograph. 



