ACTINIAN BEHAVIOR 223 



accompanied it. On the following day a second series of trials 

 was made on the same plan as the first except that the interval 

 between stimulations was reduced from half an hour to a quarter 

 of an hour. The trials began at 8.30 in the morning and ex- 

 tended to 1.30 in the afternoon. After 21 trials in which both 

 mechanical and food stimuli were used together, the mechanical 

 stimulus alone was applied. The animal retracted slightly as 

 in all former applications but there was no waving movement 

 of the tentacles. So far then as this form of experiment was 

 concerned, there was no evidence of association. 



From time to time other kinds of trials were made which, 

 while they were not always directly concerned with association, 

 were suggestive of higher nervous functions. None of these 

 yielded positive results. One may be described. Sagartia luciae 

 occurs commonly between tides and when exposed to the air it 

 is retracted. If exposed for a long time, a day or more, it will 

 dry up and eventually die from dessication. Specimens of this 

 species that had been creeping actively on a sheet of glass were 

 exposed to air, whereupon they retracted and dried slightly on 

 their outer surfaces. When this resting state had been assumed, 

 the glass was set in an inclined position in a vessel of seawater 

 and at such a level that the lower pedal edge of one of these 

 actinians was just in contact with the water, the rest of the 

 animal being exposed to the air. Although it would have been 

 easy for this particular actinian to have crept down into the 

 water, it remained inactive and fixed to the spot for over three 

 days while its mates on the part of the glass that was under 

 water crept about freely. Similar trials on other individuals al- 

 ways gave the same results; the actinians remained fixed. Had 

 they crept into the water, it would have required further experi- 

 mentation to have ascertained the reason for this, but as they 

 regularly did not, the observations give no grounds for the 

 assumption of nervous activities of an exceptional order. 



In examining the literature on the behavior of actinians two 

 tendencies are quite obvious. One emphasizes the diffuse non- 

 centralised nature of actinian responses and deals with the 

 behavior of these animsls in terms of relatively simple reflexes 



