THE PHYSIOLOGY OF NEMATOCYSTS^ 



O. C. GLASER AND C. M. SPARROW 



I Introduction 36' 



n Material and methods 362 



in Experiments with Montagua 364 



IV Experiments with the tentacles and acontia of Metridium 366 



V Experiments with isolated nematocysts 368 



Mechanical pressure 360 



Uniform external pressure 369 



Solutions 369 



Hypertonic Solutions 372 



Negative external pressure 372 



Heat 373 



Alternating current 373 



VT Rate of explosion 374 



Vn Variations in the explosive pressure 374 



VULl Application of the osmotic theory to Eolids and Ccelenterates 375 



IX The physiological effects of nematocysts on other organisms 378 



X Summary 380 



XI Literature 382 



INTRODUCTION 



Grosvenor ('03) has given a brief review of the different theo- 

 ries which have been invented to explain the discharge of nemato- 

 cysts, and has himself proposed a view which in the present state 

 of our knowledge seems the only one worth careful consideration. 

 Grosvenor's theory is that the discharge of nematocysts in Ccel- 

 enterates, and in those animals which derive their nematocysts 

 from them, is brought about by osmotic pressure. His evidence 

 is as follows : Cerata of Eolis immersed in Calberla's fluid, extrude 

 large numbers of undischarged nematocysts. If the fluid is diluted 

 with sea-water, the threads of the capsules are everted. Similar 

 results were obtained when cerata were plunged into "fairly 



* Contribution from the Zoological Laboratory of the University of Michigan, No. 122. 

 The Journal ok Experimental Zoology, vol. vi, no. 3. 



