304 



ANIMAL LIFE 



sucking blood, and the parasite will in some cases continue 

 feeding. 



Among the higher vertebrates some areas of the skin are 

 more sensitive than others. If the points of two phis be 

 pressed to the skin at a distance of less than two inches 



PIG. 341. The slipper animalcules (Paramceciuni). Photograph from life through 

 the microscope. 



apart on the middle of the human back, only one point 

 will be felt, but on the tip of the tongue two separate 

 points may be distinguished when only one twenty-fifth 

 of an inch apart. In the higher animals the sense of feel- 

 ing depends upon the presence of special nerve termina- 

 tions from which lead nerve fibers to the spinal cord or 



