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The interpretation of this phenomenon is rather difficult. 

 It is well known that when aa attached starfish la pulled off from 

 its substrate, many of the tube feet will be torn off and may remain 

 attached to the substrate for some time* The experiment shows fur* 

 ther that mioh a tube foot nay reattaoh even tho it be unconnected with 

 the radial nervous system (sea also Botazzi 1898 and Ruaso 1913)* 



It is well Vnown, also, that some times a a starfish is very 



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prone to attach its tube feet tightly to the substrate while at other 

 times the animal's energy is taken up with loooiaotion or some other 

 activity that does not entail tight attachment of the tube feet 

 (Jennings 1907)* The experiment shows also that there is a difference 

 in the behavior of the isolated tube feet which corresponds to the 

 fluctuation of the attaching reaction of an animal from time to time* 



According to Von Uexkull, the contraction of a muscle is 

 due to "Tonuft* which is metaphorically referred to as a fluid, that is 

 carried to the muscle through the nerves* Furthermore (1903) by out* 

 ting the nerve which has supplied this tonus, the "fluid* may be en- 

 trapped in the muscle, and the muscle remain contracted* Vhile this 



(t^n^e4d i<*0*lr) 



theory has not been vory widely accepted, some of its aspects are 



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partly congruent vith the behavior of isolated tube feet* 



Tube foot preparations, however, that are capable of 

 attachment do not present any differences in appearance from those 

 that are not capable of attachment* Thus they are not influenced 

 by entrapped " tonus* in the sense of Von Uexkull because "tonus" 

 elicits contraction or tension in the muscles it affects and the 

 tube feet undjr observation did not seem to differ in this respect 

 from tube feet which would not attach to a substrate* In fact they 

 differed from tube feet taken from a starfish in active locomotion 

 only in being in such a state of physiological activity that the 



