OBSERVATIONS ON THE LIFE-HISTORY OF TWO 



RARE CILIATES, SPATHIDIUM SPATHULA 



AND ACTINOBOLUS RADIANS 



JULIA E. MOODY 



From the Zoological Laboratory, Columbia University 



SIXTY-SIX FIGUBES 



I. Spathidium spat hula 349 



1. Introduction 349 



2. Material and methods 352 



3. Morphology and physiology 354 



4. Reproduction 358 



5. Encystment 360 



6. Observations on the life-history 361 



7. Regeneration 363 



8. Summary 364 



II. Actinobolus radians 365 



1. History 365 



2. Material and methods 368 



3. Morphology and physiology 369 



4. Reproduction 374 



5. Summarj' 375 



III. General considerations 377 



A. The life-cycle, senescence and rejuvenescence 377 



B. Nucleus plasma-relation 381 



C. Food habits 393 



Literature cited 396 



I. SPATHIDIUM SPATHULA 



1. Introduction 



In his ''Histoire Naturelle des Infusoires," Dujardin ('41) 

 first described Spathidium as an organism cyhndrical in form, 

 very transparent and marked with 20 to 27 dehcate, longitudi- 

 nal striations; although he speaks of the obhque truncation of 

 the anterior end he evidently observed neither mouth nor cilia 

 in this region. Mil Her in 1786 had described a form, Leucophrys 

 spathula, which with Enchelys gigas of Ehrenberg, Stein and 



349 



JOURNAL. OF MORPHOLOGY, VOL. 23, NO. 3 

 SEPTEMBER, 1912 



