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trying to walk in five different directions at once. 



Auto tony 



Another indication of this tendency is the faot that in 

 stale water or under the influance of ohbroform (Moore 1916) 

 a starfish is extremely susceptible to autoton^ Pisaster 



seems much more susceptible to this reaction if the nervous 

 system has been injured in some part. As I have observed it, the 

 reaction consists in an exaggerated tendency in the tips of the 

 several rays to migrate in their own direction and a failure 

 of this tendency to effect an orientation rf the tube feet of the 

 rest of the animal in the way that will be seen below to be 

 usual in the normal starfish* This is due to a pathological 

 sluggishness in the action of the central part of the ambulacral 

 nervous system, as seen from the fact that the tube feet in that 

 region are comparatively inactive. The raye of a Piaaster atwzatf 

 U'-vvd-t/w^tri^v^^ ' -f autotomy present an elongated appearance. 

 The tube feet at the tip pull actively, each in the direction 

 of its own ray, so that after stretching somewhat the ray gives 

 way, usually at or near the base. 



FORMATION OF THS UNIFIiiH) IMPULSE 



/ - , 



o< 



From such a picture as the above it may seem as A far call to 

 the unified behavior of the actively walking starfish. In the 

 latter each tube foot is put out in a single definite direction and 

 locomotion proceeds in a beautifully unified and coordinated 

 manner. The difference is ttm Just this, that in the unified 

 locomotor starfish, one, or more often two adjacent rays become 

 for some reason more active than the others and the coordinated 

 state which is present at their tips spteads maintaining its 

 own direction and gaining impetue, over the other rays. 



It u>\\^ .. be our purpose now to inquire into the factors which 

 give precedence to the activity of some ray or rays in the 



