148 Our Food Mollusks 



of natural selection, developed many means of protec- 

 tion, some of them very extraordinary, so that a balance 

 is established that allows a species to survive. But when 

 man makes his appearance, and domesticates wild plants 

 or animals, these equilibriums are disturbed, and com- 

 plicated results follow. 



While these conditions might be illustrated by scores 

 of interesting examples, that might be selected from the 

 observations of naturalists, it is sufficient to call atten- 

 tion to the fact that the agriculturist is constantly waging 

 a war on numerous enemies that attack every animal or 

 plant that he attempts to rear, and that would destroy 

 them without his intervention. Not only is this true, 

 but often when one foe is conquered, an entirely new 

 one appears. It is an ever changing and never ending 

 warfare. 



Naturally, the oyster culturist does not escape the ne- 

 cessity of fighting oyster enemies, and there are many of 

 them. Fortunately, natural surroundings are not greatly 

 changed by the methods of the culturist, but even the 

 slight changes that are necessary, have facilitated the 

 attacks of some enemies, and led to their rapid increase. 

 Natural oysters in dense clusters are more or less pro- 

 tected from the attacks of starfish, drumfish, boring 

 mollusks, and other foes, but when spread out singly on 

 smooth bottoms, are easily destroyed. Fortunately the 

 distribution of no oyster enemy is as extensive as that 

 of the oyster itself. Some of these foes exist only in 

 salt water, while others seem to be limited in their dis- 

 tribution by temperature. 



In the most northern of the Atlantic grounds, the 

 common starfish is by far the most destructive of the 

 oyster's foes. Fortunately it is a truly marine animal, 



