468 



THE AMERICAN NATURALIST [Vol. LV 



the physiologically anterior end (Child 9) could not be deter- 

 mined. But the antero-posterior gradient is what one would 

 expect in animals possessing fibers which conduct efferent im- 

 pulses (Tashiro 10). 



Contrary to Neresheimer (5) the animals are narcotized in 

 these solutions. 



Micro-dissection experiments showed that the coordination of 

 movement of the cytopharyngeal membranelles is interrupted 

 when the neuromotor fibers are cut. Those posterior to the cut 

 beat slower and with smaller amplitude than those anterior to it. 

 Extensive destruction of structures in the region of the neuro- 

 motor center or motorium destroyed coordinated movement of 

 the peripheral cilia. In one ease in animals isolated in gelatine 

 four zones of cilia were seen. Those of one side beat in oppo- 

 site directions to those of the other. 



A complex fibrillar apparatus ha.s been differentiated in Para- 

 mecium. It connects the membranelles of the cytopharynx and 

 the peripheral cilia and also the trichocysts with the neuromotor 

 center. Therefore, the morphology of this system suggests that it 

 is conduetile. Experimental data streim'tliens this morphological 

 evidence; first, because the antero-posn'ri-.r uT.i.licnt tliat (>\isr^ 



complex ^vstem of fibers which <-on.l,H-t , lu ,vnl n„puU ^ fnuii 

 the antcri.-r end to the ncnn>nu)1..r milM' -,.,„„! the luicn*- 



CiiAui Ks AV. Rees 



LITERATURE CITED 



1. Sharp, R. G. 



1914. Diplodinium ccaudatum with an Account of its Neuromotor 

 AppuratuH. Univ. Calif. Puhl. Zool., 1.3, VA-Vl^. 



2. Yocom, H. B. 



1918. The Neuromotor Apparatus in Fiiptntes patrlhi. Uiiiv. Calif. 



Pubi. Zool., 18, ;vM-:m, pis. m-h;. 



Taylor, C. V. 



in Euploten by the Method of Micro-dissection. Univ. Calif. 

 Publ. Zool., 19, 403-470, pis. 29-3:{. 



