AND PHYSIOLOGY. 



315 



but often, as in the Cypraea or Cowry, the mantle extends 

 over the shell. 



561. Radiates. — With the exception of the hard external 

 skeleton of these animals already described, their proper skin 

 is mostly thin and soft, allowing of great flexibility and some- 

 times of great expansion and contraction. 



The Protozoa have a very delicate, cutaneous envelope, 

 sometimes smooth and sometimes covered with cilia. 



Effect of Fright on Hair. — A Sepoy of the Bengal Army, brought as a 

 prisoner for examination before the British officers, was terribly affrighted, 

 trembled like a leafj and was almost stupified with fear. Such was the shock 

 upon his brain that his hair, from a glossy jet black, became gray within the 

 space of an hour, the subject being only twenty- four years of age. 



Also a boy, let down from a high cliff on the coast of Scotland to get eggs 

 of sea-birds. He, in defending himself from the birds with the sword, struck 

 the rope by which he was suspended, and cut off every strand but one. 

 When drawn up his hair was white. 



Maria Antoinette experienced a change in the color of her hair during ona 

 night's excessive fear. 



