-US- 

 time, the 'leg* which corresponds to it becomes inflated and elonga- 

 ted, Finally it is aeon that on cessation of the pressure the ball* 

 refill and the legs become empty and shorten themselves, and it is 

 nothing more than this that the starfish does in extending its lega- 

 to press upon the balls, aa one may do at any time --vith his fingsr* 

 It is easy to imagine a thousand ways in which the starfish can do 

 this. The compressed balls discharge their -tater into the legs which 

 they inflate and thus extend, but when the starfish ceases to press 

 on the balls, the natural elasticity of the legs, -*hlch is consider* 

 able causes them to shorten* These legs, thus elongated the animal 

 uses in locomotion by t*.****^ extending them out toward the body to 

 which traa animal wishes to move and attaching to it at a vary acute 

 angle* The strength -vith which the leg remains affixed to this body 

 while trying to make a right angle -sith this same surface obligee 

 the animal to approach*" 



of the withdrawing reflex as a responsa to contact stimulation of 

 the disk* The intargrading steps depend upon the presence to a 

 greater or less degree of a looozcotor tendency* This expresses it- 

 self, in the inverted or suspended starfish, as already shown by an 

 orientation of the extended tube feet in the direction of the phys- 

 iological anterior* If the locouotor impulse is not very strong, 

 the only modification perhaps that will toe observable in the with- 

 drawing reaction, will be an exaggeration of the tendency to extend 

 after the contact stimulation and before the withdrawal* 



With the increase of the locomotor impulse comes a change 

 in the behavior of the tube foot wMoh integrates both with the with- 

 drawing response and the step reflex* this change is a further in* 

 crease in the above noted tendency to extend, caused no doubt by an 

 increase in the tension of the ampullar muscles* This complicates 

 the withdrawing action, and then results, for reasons which we will 

 take up later a more rapid contraction of the muscles on one side of 

 the pedicel than on the other* This gives rise to a lateral movement 

 of the tube foot 'thich increases in extent with the increase of the 

 locoraotor impulse, from a slight bending (fig* 3) of the tube foot 

 to one side, to an active lashing back (fig* 4) of the disk with 

 sufficient force to throw a grain of sand some few centimeters* 



