GRASPING ORGAN OF DENDROCOELUM LACTEUM 379 



applied from a capillary tube to their lateral margins. In no 

 case was there a response of the whole worm, as when feeding 

 begins, though in each instance a local expansion of the side 

 of the body occurred where the sugar solution had been applied. 

 As a preliminary experiment, before removing their heads, all 

 the worms were tested with a brown-sugar solution, and found 

 to feed upon it in a normal manner. The heads of the decapi- 

 tated worms were kept, each in a watch glass, and subjected to 

 the same stimulus as that used on the trunk of the worm. They 

 responded by coming up to the tube and remaining close to it, 

 the grasping organ being agitated in the same manner as in the 

 normal worm about to begin feeding. Occasionally a head 

 would circle away from the tube but it always came back again. 



These experiments confirm the previous one, in that they 

 show that the receptors for the feeding reactions are located 

 upon the head of the worm. One might object to drawing this 

 conclusion on the grounds that animals whose heads had been 

 removed might be expected, as a result of the operation, to fail 

 to respond normally; but since the heads, which had been sub- 

 jected to as great a shock as the trunks, if not a greater one, 

 reacted normally, this objection can have no weight. In order 

 to determine whether the grasping organ itself, or the auricular 

 appendages were the receptors, the following experiment was tried. 



The grasping organ, after having been stimulated to action, 

 was removed by catching it with forceps and pulling it out. 

 The results were surprisingly uniform; worms without the grasp- 

 ing organ did not attempt to feed. It would appear from this 

 experiment that the receptors for the feeding reflex, are located 

 probably on the sucker itself. 



Mechanical and certain chemical stimuli (as a twenty per 

 cent solution of sodium chloride) call forth a rapid forward 

 movement of the animal, like that of some leeches, produced 

 by (1) extending the body, (2) attaching the grasping organ to 

 the substratum, (3) releasing the posterior end, contracting the 

 body, (4) attaching the posterior end, and then again (5) carry- 

 ing the body forward, thus repeating the whole operation. If 

 the grasping organ is removed, the animal may still progress 

 in a leech-like manner, attaching itself by the action of the 

 general ventral surface of the anterior end combined with that 

 of the margins of the body in the same region. If the head is 



