350 Vniversity of California Publications in Zoology [Vol. 20 



opposite directions to those on the other. On the other hand, severe 

 injury to other parts of the body than the motorium did not affect 

 the coordinated movement of the cilia. 



Jennings and Jamieson (1902) found that pieces of Paramaecium 

 and other ciliates behave not unlike intact animals, except that in the 

 smaller pieces the movements are more feeble. These observations I 

 easily confirmed in the case of Paramaecium. In a small piece from 

 an animal isolated in gelatine not over one-fifth as large as the intact 

 organism, the cilia continued to vibrate normally for at least five 

 Ininutes. Five such cases were observed, three in anterior pieces and 

 two in posterior pieces. In no ease, however, were the cilia observed 

 to reverse their movements in these small pieces. Intact animals in 

 gelatine reverse the movements as a rule every few seconds. In all 

 cases, however, all the cilia of the piece beat in iinison. 



The evidence indicates that, while the cilia may beat in the absence 

 of neuromotor impulses from the neuromotor center, this center does 

 exert an influence through the neuromotor fibers in coordinating and 

 integrating the direction of vibration of the cilia as a whole. 



DISCUSSION 



As intimated by earlier writers (Taylor. 1920), the main objec- 

 tions to the idea of conductility in fibrillar systems of the Protozoa 

 come from advocates of the cell theory who fail to recognize that 

 complexity of structure may be attained within a single cell and 

 without cell division and division of labor among its products. The 

 nucleus has been the main object of stiidy of those who have investi- 

 gated Protozoa. 



But no one will deny that the protoplasm of Paramaecium con- 

 ducts stimuli. Else the complex behavior exhibited in the avoiding 

 reaction (Jennings, 1901) would be impossible. This being the case, 

 the structures best adapted to conduct stimuli are those of the neuro- 

 motor system. 



Sharp (1914) developed a clever argument in discussing the 

 neuromotor apparatus of DipJodiniinn. He ascribed to the fibers one 

 of three functions, that of support, of contractility, or of conductivity. 

 Then, by the method of elimination, he showed that the fibers are 

 conductile. 



