294 LIGHT AND THE BEHAVIOR OF ORGANISMS 



minutes, whereas the intervening contractions seldom 

 lasted more than one and a half minutes and are usually 

 less than thirty seconds." 



Hargitt (1909) extended these observations on the vari- 

 ability in reactions of the tubicolous annelids. Of especial 

 interest are his results with experiments on specimens 

 taken in deep water where shadows are very faint as com- 

 pared with specimens taken from shallow water where 

 changes of light intensity are striking. The following 

 tables illustrate the character of these reactions (pp. 170, 



TABLE VIII 

 Showing reactions of specimens from deep waters ^ 



August 9, II A.M. August 9, 2 P.M. 



Temperature, 22° C. 



Temperature, 22,5° C. 



I 

 2 



3 

 4 



5 

 6 



7 

 8 



9 

 10 



II 



12 



13 

 14 



15 

 16, 



!;■ 

 18. 



19' 



20. 



A 



4-12 



B 



+ 10 

 o 

 o 



+10 



+ 



o 



+ 



o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 



D 



E 



+ 



o 



o 



A 



B 



+ 18 



+35 



+ 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



o 



D 



+30 



E 



+ 20 



^ The numbers preceded by + represent time in seconds animals re- 

 mained in tubes after stimulation. Minus sign indicates failure to respond; 

 zero indicates that animal was in tube when stimulus was applied. The 

 stimulus consisted in turning off a i6-candle-power electric lamp. The 

 intensity is not recorded. Interval between successive stimuli, usually 

 5 minutes. (Hargitt, 1909, pp. 159 and 170.) 



