SOME CHEMOTROPIC AND FEEDING REACTIONS OF 

 PLANARIA MACULATA. 



ROSALIND WULZEN. 



(From the Rudolph Spreckels Physiological Laboratory of the University of 



California.) 



When a hungry 1 Planarian is placed in a finger-bowl of water 

 a piece of liver has been lying for some minutes, the worm 

 moves about the dish until it enters the diffusing meat-juice. 

 It pauses at once and extrudes the pharynx. This waves about 

 for a few seconds and is withdrawn. Then the worm takes up 

 its course directly toward the meat and, reaching it, begins 

 feeding. The same reaction is seen when the worm is gliding on 

 the surface film and a bit of egg-yolk is floated near it. This 

 preliminary extrusion of the pharynx, although regularly appear- 

 ing when hungry worms first come into contact with meat-juice, 

 is very transitory. It does not occur again if the worm leaves 

 the juice and reenters it on its way to the meat or if it is placed 

 in an extract of meat and left to wander about there. 



If, however, a section is made through the worm behind the 

 cephalic lobes and anterior to the pharynx the result differs. 

 Directly after the cut the worms move about in an active manner 

 though they eventually come to rest. If while still moving 

 they enter a region of diffusing meat-juice they often stop. The 

 pharynx is extended and remains so; feeding begins upon the 

 juice itself and may continue until the body has swollen and 

 become lighter colored as in ordinary feeding. Often the reaction 

 is not so prolonged but it is always more free, and persistent than 

 in uncut worms. From this a natural inference would be that 

 such pieces placed directly upon meat would respond with the 

 feeding reaction, and this is true. The posterior portion of any 

 hungry worm will feed when placed upon a fresh piece of liver. 



1 Worms which had been fasting several weeks were used for these reactions. 

 Well-nourished worms do not furnish good material, as their sensitivity to chemical 

 stimulation is low compared to that of fasting worms. 



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