VI 



CONTENTS 



Osmotic and Ionic Regulation inAquatic Invertebrates 229 



James D. Robertson, Ph.D., F.R.S.E., Senior Lecturer, Department of 

 Zoology, University of Glasgow, Scotland. 



Recent Advances in Knowledge of Invertebrate Renal Function 247 



Arthur W. Martin, Ph.D., Professor of Zoology, University of Wash- 

 ington, Seattle, Washington. 



Some Features of the Physiology of the Tunicate Heart 277 



B. J. Krijgsman, Ph.D., Research Fellow, and Nel E. Krijgsman, 

 Division of Comparative Physiology, Department of Zoology, University 

 of Cape Town, South Africa. 



The Rhythmic Nature of Life 287 



Frank A. Brown, Jr., Ph.D., Morrison Professor of Biology, North- 

 western University, Evanston, Illinois. 



