CONTRIBUTIONS FROM THE ZOOI-OOICAL LABORATORY OF THE MUSEUM OF COMPARATH'E ZOOI OQY AT 

 H.\HVARD COLLEGE, NO. 271 



THE RHYTHMIC PULSATION OF THE CLOACA OF 

 HOLOTHURIANSi 



W. J. CROZIER 



THIRTY-ONE FIGURES 



CONTENTS 



I. Introduction 298 



II. Pulsation in the intact animal 299 



a) Morphology of the pulsating parts 299 



b) The sequence of movements 302 



c) Correlation with size 307 



III. Co5rdination of the pulsating complex 311 



a) Effects of autoevisceration 312 



b) Effects of amputation 313 



c) Mutilation experiments 320 



d) Summary 324 



IV. Relation of pulsation to temperature 325 



V. Action of depressing agents 331 



a) Anaesthetics 331 



b) Alkaloids 332 



VI. Relation of pulsation to oxygen and metabolic products 334 



a) Oxygen 334 



b) Carbon dioxide 336 



c) Urea 336 



d) Light 336 



e) Summary 338 



VII. Influence of osmotic pressure 338 



a) Dilutions of sea water 338 



b) Non-electrolyte solutions 342 



VIII. Ion effects ." 343 



a) Single salts 343 



b) Mixed salts 346 



c) Hydrogen-ion concentration 351 



IX. Summary 352 



X. Bibliography 354 



' Contriljutions from the Bermuda Biological Station for Research, No. 43. 



297 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 20, NO. 3 

 APRIL, 1916 



