FOOD AND THE NERVE-NET 149 



this explanation is correct, as there is good reason to 

 suppose it is, the responses of the tentacles are like those 

 of the oral cilia in that they are not especially dependent 

 upon the condition of the animal as a whole. As Gee 

 (1913) states, "the view that the seat of the modified re- 

 sponsiveness lies very largely in the individual tentacles 

 is more clearly in accord with what is known of the struc- 

 tural organization of the sea-anemone than that the ani- 

 mal acts as a unit." 



The feeding habits of sea-anemones thus prove on ex- 

 amination to consist of operations none of which neces- 

 sitate the assumption of activities other than those con- 

 sistent with the nature of the nerve-net. There is no rea- 

 son whatever to resort to the hypothesis of a controlling 

 nerve center. All the activities are strikingly local and 

 the changes that they exhibit are apparently entirely due 

 to fatigue. In these respects they are in strong contrast 

 with the feeding habits in the higher animals, a process 

 which has become so deeply wrought into the make-up 

 of these forms that its relation to the animal as a whole 

 is most profound. While almost every one of the ele- 

 ments involved in the feeding of actinians may be ex- 

 perimentally isolated and made to act for itself in a re- 

 markably local way, scarcely any such independence is 

 observable in the parts concerned in the similar opera- 

 tions of higher animals ; the jaws and their muscles, buc- 

 cal glands and so forth in these higher animals exhibit a 

 highly unified action dependent chiefly upon central nerv- 

 ous connections such as is scarcely suggested in actinians, 

 but as isolated elements they have almost no reactive 

 power at all as compared with what is possible in sea- 

 anemones. The feeding habits in actinians then empha- 

 size the relative independence of parts rather than the 

 action of the organism as a whole (Parker, 1917 d). 



