THE LIVING STRUCTURES 117 



for life. It is encased in a star shaped structure, strong 

 and tough as bone and its star shape makes it a disagree- 

 able substance to swallow by any larger animal. The 

 cells that build this structure have been able to hold their 

 own in the struggle for existence and they have reason to 

 be proud of the progress they have made in the past ages. 

 We might consider next the species of sea plant or ani- 



FIG. 14. Starfish. General view of the ventral surface, showing the tube- 

 feet. 



mal called the antedon. This animal fastens itself on the 

 sea bottom. It starts to grow in the same manner as any 

 other animal. The single individual cell who starts the 

 building of this animal, first swims about in the ocean, 

 then finally settles down and builds this structure. The 

 secret of the success and progress of this individual is in 

 the fact that it covers itself with such disagreeable build- 

 ing material that other animals will have nothing to do 

 with it and cannot use it as food. This animal has been 



