MOVEMENTS, ETC., OF FRESn-WATER PLANARTANS. 521 



pendent of the brain. There was? found to be co-ordination 

 between the anterior and posterior pieces of a worm in 

 which the lateral longitudinal nerves had been cut, but in 

 which a narrow connecting strip of tissue had been left 

 between the pieces. In P. torva Loeb states that posterior 

 parts of the body which have been separated by a ti-ansverse 

 cut from all connection with the brain crawl " ebenso munter 

 weiter, wie die orale Hiilfte." The reaction of this form to 

 changes of light intensity is discussed in considerable detail, 

 it being shown that in strong light the organism is stimu- 

 lated to active movement, while iii the shade it remains quiet 

 or moves very slowly. This was found to occur as well in 

 decapitated as in normal worms. The " stereotropic " reac- 

 tion in this form is also mentioned. In concluding, the 

 author holds that in worms there is no '^associative Gedacht- 

 niss," and hence no consciousness. These results have been 

 recently incorporated without essential change into a larger 

 work (Loeb : 00). 



In an earlier paper Loeb ('93) first described the reactions 

 to light of Planaria torva. These residts were incor- 

 porated without essential change into the '94 paper men- 

 tioned above. 



Hesse ('97), in his morphological studies on the eyes of 

 flat-worms, devotes a section to the subject of the reactions 

 to light of Euplanaria gonocephala and Dendrocoelum 

 lacteum. His results are confirmatory of Loeb's, nothing 

 of particular significance being added. 



Steiner ('98) found that posterior pieces of Planaria 

 Neapolitana (=Stylochus pilidium, Lang) separated 

 from the brain by a transverse cut would move al)out freely 

 after recovei-y from the operation. He believes this ability 

 to move is conditioned by the presence of ganglion-cells in 

 other parts of the body than the brain (along the lateral 

 nerve-cords) . 



Parker and Burnett ( : 00) have recently made a thorough 

 study, using very careful expei-imental methods, and treating 

 the results statistically, of the reactions of Planaria 



