MOVEMENTS, ETC., OF l''KE8H- WATER PLANARIANS. 519 



motiou of this remarkable form lie saj^s^ '^lu Heteroplana 



the locomotion is usually conducted in a somewhat 



one-sided fashion/' and he furthermore fig-ures the animal 

 as constantly moving towards the left. It is to be regretted 

 that no reference is made to how this form reacts to stimuli, 

 as it would be of great interest to know whether the reactions 

 are asymmetrical, and in general how they compare with 

 the normal planarian type. 



A series of papers by Morgan ('98, : 00, : 01) contains 

 numerous references of importance on the movements of cut 

 and regenerated specimens of various fresh-water planarians. 

 He finds ('98), in confirmation of van Duyne, that in two- 

 headed individuals each head tends to move in its own proper 

 direction. In the case of a heteromorphic form Avith two 

 heads pointed in opposite directions, this likewise held true ; 

 but one component being stronger this determined the move- 

 ment of the whole. The lack of movement in certain forms 

 of cut pieces is also noted. In his : 00 paper Morgan notes 

 the readiness with which " Planaria, sp. " ^ and Planaria 

 maculata take food, although no account is given of the 

 method of the feeding reaction. An interesting observation, 

 and one of considerable theoretical importance, is also re- 

 ported in this paper. In an individual split longitudinally in 

 the median line from the posterior end forward, in which the 

 two parts were united only by a small connecting band of 

 tissue at the anterior end, it often appeared " as though these 

 pieces would pull apart, but as soon as the tension on the 

 connecting band becomes too strong, the rest of the piece, by 

 a sort of adaptive response, ceases pulling in its former 

 direction." In the most recent ])aper cited (: 01) Morgan 

 corrects a statement o£ Bardeen ^ regarding the feeding of 

 Planaria. It is maintained (and I may mention at this 

 point that my own observations agree entirely with those of 

 Morgan) that Planaria "responds freely" to food sub- 



1 Later ideiililied by Woodworth as Planaria lugubris. 

 - To be reviewed later. 



