THE DIVING STRUCTURES 151 



necessary and not otherwise. The actions of the cells in 

 building hair are brought about precisely in the same 

 manner as the actions of man in making and covering 

 himself with heavy clothing whenever it is necessary and 

 not otherwise. It is his needs and desires and require- 

 ments that spur him to action. It is of course true that 

 any person in a cold climate who does not have sense 

 enough to make and cover himself with clothes will per- 

 ish and be exterminated and this would be true of those 

 animal building cells. The builders of every animal have 

 sense and intelligence enough to increase the length and 

 thickness of the hair if necessary in the same manner that 

 man has, to provide himself with the clothes required. 

 The act requires skill and intelligence sufficient to gather 

 the material and build the structure, be it hair or clothes. 

 One requires just as much intelligence as the other. 

 There is a production of hair for a purpose, just as there 

 is a production of clothes for a purpose, just so we find 

 structures of all kinds produced in the living world for a 

 purpose, as for instance, the shells of the sea animals: 

 some are thick and powerful in order to resist the crush 

 of the water pressure in the deep ocean, or the crash and 

 hammering of the waves on the shore ; other shells are 

 thin like those which move over the mud in shallow still 

 water. The shells are the houses in which colonies of cells 

 live. Experience shows that if you plant them in deeper 

 and rougher waters they will build a shell stronger and 

 thicker, just as you might expect, for if the builders act 

 with intelligence in one place they will also do so in other 

 places. This fact has been shown in thousands of ways-, 

 for instance, one class of cells will take charge of the work 

 of another class, the cells in charge of the mucus mem- 

 brane will build an outside skin covering if necessary, or 

 the cells in charge of the ^utside skin will refuse to build 



