CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF 

 COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. E.L.MARK, Director. No 204. 



THE REACTIONS OF SPONGES, WITH A CONSIDERA- 

 TION OF THE ORIGIN OF THE NERVOUS SYSTEM 



G. H. PARKER 



Professor of Zoology in Harvard University 

 With Three Figures 



1 Introduction I 



2 Stylotella under natural conditions 2 



3 Structure of Stylotella 5 



4 Reactions of Stylotella 9 



A Movements of the oscula 9 



a Mechanical stimulation 10 



h Injury 15 



c Chemical stimulation 16 



d Heat and cold 19 



e Light 19 



B Movements of the dermal pores orostia 19 



a Mechanical stimulation 22 



h Injury 24 



c Chemical stimulation 24 



d Heat and cold 26 



e Light 26 



C Movements of the body as a whole 26 



D Currents 28 



E Coordination of reactions 32 



5 Origin of the nervous system 34 



6 Summary 38 



7 Bibliography 40 



I. INTRODUCTION 



Previous attempts at the discovery of the nervous system of 

 sponges have been made almost exclusively from an anatomical 

 standpoint and with such negative results that Vosm^r and Pekel- 



The Journal of Experimental Zoology, vol. viii, no. i. 



