<>N THE BEHAVIOR OF TUBICOLOUS ANNELIDS. QI 



ment." Unfortunately for such explanation "free-swimming 

 form-" are rarely present in this aquarium, the only specimens 

 during my observations being the slow ancTdelicate moving little 

 sea horse, Hippocampus, whose presence among the relatively 

 colossal Spirographis could hardly be of more influence as 

 ,i disturbing factor than a few sparrows in an oak forest! In 

 fact -pre imrns of Hippocampus had been kept for weeks in one 

 nl' tin aquaria in which my special experiments \\ere being made 

 .ui'l \\mild frequently attach themselves by their delicate pre- 

 hrn-ilr tail- to the tubes of Spirographis but without the le.i-t 

 r\idm. e !" disturbance of any sort. One often finds the tubes 

 ' it these .imielids more or less loaded with tunicate-, -p-nu' - 

 li\ilr<ii<l-. etc., but there was never any appreciable sign "I 

 di-iurbaiice therefrom so far as their orientation was concerned. 

 I think it must be rather obvious that the behavior exhibited 

 b\ these creatures under the sub-natural conditions of tli. -< 

 ma^iiiti' ' nt aquaria conforms in all essentials with that found in 

 tin- r\pi rimental tanks, and under both these tests then- seems 

 to be a fair equivalent of that to be observe* 1 in their nati\e 



habitat. 



CONCLUMV. REMARKS. 



Tin Inn ^iiing account, especially when taken as a part ot the 

 more extended observations already repeatedly citr<l '06, '09 

 must make it more or less evident that so far from affording any 

 -iippun lo the sweeping assumption of the identity nl animal 

 and plain hrliotropism, based on the behavior of these organisms. 

 siKuid ,-sts, if indeed one might not say warrants, tin \ -r\ 



opposite. One might even go a step farther and saj that ii 



us extremely doubtful whether the behavior of Hy<lriii<-s, 

 rnniti>, eras, Spirographis, or any of the tubio>lou> annelids may 

 l.r interpreted as an expression of tropi-m- at all. Without 

 -eeking in any way to discredit the possible role of light in rrlaii<m 

 to certain aspects of behavior, it may vet be fairly doubted 

 whether it sustains any such determining influence as has been 

 claimed by the exponents of the tropism hypoihesi-. Indeed the 

 tacts \\hich ha\e been passed in review show beyond rea- -liable 

 doubi that in relation to these organisms it can have but a sub- 

 ordinate and incidental place. It seems perfectly certain that 



