632 IJAYMOND PEARL. 



not localised with refeieucc to tlio sLiiuulus with the utjiial 

 precision. 



The ''gripping" of the food substance by the anterior part 

 of the worm is a very characteristic feature of the normal 

 food reaction. Its exact form depends on the configuration 

 of the food or other body "gripped." In its most typical 

 form, where the food material is in the form of a cylinder, or 

 approximately such, the action reminds one of the action of 

 the human hand in grasping a stick. The tip of the head 

 closes over the material in the same way that the fingers do, 

 while the region just behind the auricles bears the same 

 relation as does the proximal part of the palm, just in front 

 of the wrist, in grasping. After the head has been placed 

 over the material in this way it can be seen to contract 

 rather strongly, and thus literally squeeze the food. In case 

 the surface contour of the food does not admit of this reflex 

 being carried out in its typical form, as close an approxima- 

 tion to this is made as possible. To compare again with the 

 human hand, when the surface is flat, or forms the surface of 

 a cylinder of large radius, the ventral surface of the head is 

 pressed closely to it, the tip attempting to dip in, as it were, 

 below the surface, in just the same way that a man "claws" 

 with his finger tips in attempting to obtain a liold on a 

 similarly configured body, too large for complete grasping. 



While the "gripping" is in general a very characteristic 

 feature of the food reaction, it may be omitted in rather 

 exceptional cases. The cause for the omission where it 

 occurs, or any laws governing the matter, I have not been 

 able to discover. A necessary accompaniment of the 

 "gripping" of the food is the cessation of the forward 

 movement ot" the animal as a whole. This pause when the 

 food is first touched by the anterior end and before the worm 

 passes up on to it, occurs in practically every case, whether 

 the grijipmg accompanies it or not. The length of the pause 

 is, of course, considerably greater when the " gi'ipping " 

 occurs than when it is absent. 



The function of the "gripping" of the food material before 



