1922] Rees: The Neuromotor Apparaius of Farnmaecium 341 



section fifteen microns tliick which was fixed in picro-niereuric, 

 stained twelve hours in haematoxylin, and destained until almost 

 white. A small body to which the cytostomal fibers converge may 

 also be seen in well destained whole mounts. The fact that all the 

 fibers of the system converge toward a point in this region suggests 

 a motorium : a body that functions as a coordinating center or in some 

 way provides a contact of fibers effecting a basis for such inter- 

 connection and coordination. 



Peripheral Fibers 



For convenience the neuromotor system will be described under 

 the two headings, peripheral fibers, and cytopharyngeal fibers. The 

 peripheral fibers are arranged in two whorls, one on the oral, the 

 other on the aboral side (figs. A and B, or. ivh., ah. tch.; pi. 32, figs. 

 1-6, pi. 34, figs. 13-19). 



The oral whorl is the more extensive, covering the entire oral side 

 and extending, on the left, over part of the aboral side. The fibers 

 lie very near the surface, impinging upon the endoplasm as they 

 approach the neurom6tor center. They are gray when stained with 

 iron haematoxjdin, and red when stained with Mallory's. The thick- 

 ness of the individual fibers has not been determined but they appear 

 very fine when seen under a magnification of 1330 diameters. In the 

 oral groove when followed from their diverging ends in the ectoplasm 

 toward the neuromotor center, their course is obliquely caudad to 

 the margin of the cytostome, where they turn and converge obliquely 

 cephalad. Over the remainder of the surface, they run in gracefully 

 curved lines directly toward the neuromotor center. The anastomos- 

 ing ends in the ectoplasm are very numerous and profusely branched, 

 forming a thick fibrillar complex (figs. A and B; pi. 32, figs. 1, 3, 4; 

 pi. 34, figs. 13-19). 



The fibers of the aboral whorl converge, forming a large V-shaped 

 figure with the apex on the left, opposite but slightly posterior to the 

 cytostome (fig. B; pi. 32, figs. 2, 3, 4). Here they appear to dip 

 into the endoplasm in their course toward the neuromotor center. 

 The ramifications of the fiber ends of this whorl resemble, in every 

 respect, those of the aboral whorl. 



The meeting places of the fibers of the oral and aboral whorls in 

 the ectoplasm cannot be made out very distinctly, because, in order 

 to see them, the animals must lie either on their right or their left 



