ON THK BEHAVIOR OF TUBICOLOUS ANNELIDS. 87 



On March 25, ten days after the specimens were installed, only 

 had assumed a nearly vertical aspect. Others showed 

 variou- phases of orientation, from ten to twenty, or thirty, or 

 fifty dej of elevation above the bottom. 



< )n April i. the following is the record. Four -pecimen- with 

 :^ill- directed more or less toward the light; two with a vertical 

 attitude; three oriented at right angles to direction of light, and 

 facing darkest end of tank; nine remain oriented in original 

 po-ition, /. i\, facing away from light. The t\\o -u-pemle<l -peci- 

 ini 11- lieha\e almost exactly as in the previou- case; that i-. one 

 pcr!e< il\ unchanged and the other curved a\\a\ tn>m the pipe. 

 Tim- .tiler m-arlv two weeks half of the entire lot remain abso- 



l-ii. i i- .in finl view of an experimental aquarium, tin- li.^lu o>min.n 

 iiv;lit -iik .it * ' n tin- i-ii;ht specimens shown only niu- i- :.n inv; tin- liKl 

 \<-i tii .il. the others facing the dark side of tank. 



is 



hilelv unrli.ui-.'d ; of the others onl\ ti\e ^Imu any \IT\ clear 

 rea( lion to p.^ibk- light stimulus. The experiment- o mi inued 

 under d.iih observation until April \2, a |)erio<l ot one month, 

 \\iili a tmal remnl as follows: Four -pet inien- -lm\\ a distinct 

 curvature t<>\\anl the light; nine show ju-i a- distinct inclination 

 a\\a\ tioni the light, in other \\oriU remain as ori-inalK fixed 



except the slight curvature upward ; two are almost vertical ; the 



other three occup\ portions at right an^le- t<> the line of light. 



