author's abstract of this paper issued 

 by the bibliographic service, may 22 



THE ROLE OF THE NERVOUS SYSTEM IN THE 



LOCOMOTION OF CERTAIN MARINE 



POLYCLADS 



J. M. D. OLMSTED 



Hopkins Marine Station of Stanford University and University of Toronto 



During experiments on the regeneration of polyclad turbel- 

 laria of Monterey Bay, California, it was- noticed that there were 

 pronounced changes in locomotion following certain operations 

 which involved the central nervous system. 



Three species were studied with reference to the control of 

 locomotion by the nervous system, Planocera californica, Phyllo- 

 plana littoricola, and Leptoplana saxicola, with a few observa- 

 tions on Euryleptotes cavicola. The methods of locomotion are 

 the same in the first three species, the chief differences lying in 

 the rate of progression^ — L. saxicola being the fastest moving and 

 P. californica the slowest — and also in the relative frequency of 

 each method in the different species. 



A general account of the locomotion of polyclads is given by 

 Lang ('84) in his monograph on the polyclads from the Bay of 

 Naples. A more detailed account of the locomotion of Lepto- 

 plana tremellaria, also from the Bay of Naples, is given by Child 

 ('04), and of Leptoplana lactoalba var. tincta from Bermuda by 

 Crozier ('18). Child states that there are two chief methods of 

 movement in L. tremellaria, 'swimming and creeping.' The for- 

 mer is an 'undulating movement' of the margins of the body, the 

 latter involves 'both muscular and ciliary activity.' "When the 

 animal is moving quietly — the cilia afford the chief motive power, 

 although the slight muscular movements of the margin of the body 

 are almost constant, portions being lifted from the substratum, 

 brought forward, and again attached." But when strongly 

 stimulated, "movements occur in rapid alternation on the two 



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