UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 20, No. 10, pp. 243-300, pis. 27-28, 15 figures in text May 8, 1922 



ON BALANTIDIUM COLI (MALMSTEN) AND 



BALANTIDIUM SUIS (SP. NOV.), WITH 



AN ACCOUNT OF THEIR NEURO- 



MOTOR APPARATUS 



BY 



j. DALEY MCDONALD 



CONTENTS PAGE 



Introduction 244 



Acknowledgments : 245 



Material and technique 245 



Occurrence and geographic distribution 246 



Studies of living organisms 246 



Systematic position of genus and species 248 



Balantidium coli 249 



Balantidium suis sp. nov 250 



Method and use of measurements 254 



Other specific characters 258 



Balantidium from man 261 



Morphology 262 



Ectoplasmic structures 263 



Pellicle , 263 



Ectoplasm 266 



Cilia 270 



Basal apparatus of cilia 271 



Ciliary movements 273 



Cytostome 276 



Oral plug 280 



Contractile vacuoles 280 



Endoplasmic structures 282 



Endoplasm 282 



Food vacuoles , '. 282 



Macronucleus 282 



Micronucleus 283 



Neuromotor apparatus 284 



Motorium .' 285 



Circumoesophageal fiber 285 



Adoral ciliary fiber 286 



