The Mid-Winter Meetings. 199 



responsive to light, and this sensory sense is located chiefly in the tentacles and oral 

 regions of the body. S. leucolena, while less sensitive, is yet evidently so in strong 

 light. Exposed to direct sunlight it quickly closes up into a hemispherical mass, 

 or creeps over the edge of the rock or shell into shaded portions of the aquarium. 

 In its native haunts it may be found protruding its crown of tentacles from a crevice 

 while the body is hidden. 



Sagartia luciae is a free living species found abundantly almost everywhere, on 

 rocks in open pools, or on floating fucus, and freely exposed to direct sunlight, 

 action of waves, etc. Of similar habit is Metridium marginatum. Neither of 

 these species seems in the least degree responsive to photic stimuli. Under a strong 

 beam of sunlight reflected directly upon them for ten minutes they showed no 

 response whatever. 



These facts, together with others as to food habits, etc., render it quite certain 

 that their behavior is due to several factors, and that in response to light there is an 

 evidence of adaptation involving varying physiological conditions, of which the 

 burrowing habit is one of several expressions. 



Further Observations on the Behavior of Tubicolous Annelids. By Chas. W. 

 Hargitt, Syracuse University. 



Following up the work done on these animals and reported elsewhere, the writer 

 has extended the observations to aspects of behavior other than those already 

 recorded. Three points are concerned in the following observations: 



First, a study of behavior under natural conditions of environment. This has 

 been possible in quiet pools near low tide lines. Experiments on Hydroides 

 dianthus with shadow stimuli, or light intensity of varying degree, under these 

 conditions have confirmed in all essentials those made last year. 



Experiments as to tactile responses showed considerable variations as compared 

 with the former series. This may be attributed to the fact that specimens living 

 under these conditions become more or less inured to similar stimuli from the actions 

 of waves which naturally buffet them almost constantly. 



Second, experiments on the relative sensory acuteness of specimens from deep 

 water, about twenty fathoms compared with those from shallow waters, one to 

 three or four fathoms. In cases tested there were shown a definite preponderance 

 of positive reactions among tne latter, and a corresponding preponderance of nega- 

 tive responses in the former. 



Third, a comparative study of the aspects of behavior shown in the growth of 

 colonies taken from shore waters, subject to the action of waves, and those from 

 quiet waters of bays, etc., shows an unmistakable variability in the aspects of the 

 tubes, which clearly indicates environmental adaptation. Furthermore, specimens 

 growing in an environment, such as marly bottom, or silt, or other similar condition, 

 show the same evident response of adaptation. On the other hand, specimens 

 growing along shore lines, or on rocky bottoms, show likewise the unmistakable 

 response natural to such condition. Not a single colony among hundreds along the 

 shore lines showed any free and vertical tubes. Likewise specimens dredged from 

 muddy bottoms showed the erect and vertically directed tubes which would bring 

 the animals above the obstructing mud. 



Any careful consideration of the facts would hardly fail to convince one that no 

 single factor, such as heliotropism, or geotropism, or any other tropism alone, was 

 adequate for their explanation. 



