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ANIMALS 



mit the stimulus to the sensory element but are not themselves 

 sensitive. 



362. The sensory elements found in the skin of Vertebrates 

 are of various types which may be divided into two classes. In 

 one class the fibre ends in a bushy system of branches which 

 penetrate among the other normal elements of the surrounding 

 tissues. In the other class the fibre may end with or without 



Fig. 76. — The blue crab. View of the region around the mouth to show the 

 groups of cuticular hairs, which are in large part sensory. X i 1/2. 



terminal branching, but in either case there are always some of 

 the cells of the surrounding tissues modified to form a special 

 stimulating organ. The first class, the free nerve terminations, 

 are found chiefly in the deeper layers of the epidermis, though 

 they may also be found in the dermis. The second class, which 

 for want of a better name may be called sensory corpuscles, 

 are found chiefly in the superficial and deeper layers of the 



