CILIATE FIBRILLAR SYSTEMS 241 



the ectoplasm, and extend to the posterior end of the animal. These 

 myonemes are "closely associated with the basal granules." Commissures 

 connecting the basal granules form a close network over the entire body. 

 Supporting fibrils from the nuclear membrane, the endoplasmic cone, and 

 the contractile canal extend to the peripheral ectoplasm (Fig. 87) . 



The deeply staining mass was interpreted as a niotorium because "" (1 ) 

 it is connected, directly or indirectly, with all parts of the fibrillar system; 

 (2) it is near the anterior end of the ciliate; (3) if, with this mass, the 

 sucker is removed, the animal loses its power of worm-like forward 

 movement even though the cilia continue to beat; and (4) a toxic sub- 

 stance acts first upon the anterior part, particularly the sucker, where- 

 upon the animal ceases its forward movement." 



Methods 



Fixatives: Schaudinn's and Zenker's. 



Stains: Delafield's and Heidenhain's haematoxylin ; also Kolatschev's osmic 

 impregnation, as outlined by Bowen ; Yabrofif method. 



Ichthyophthirius (MacLennan, 1935). — The longitudinal fibrils con- 

 necting the basal granules beneath the ciliary rows of the body surface 

 are linked together anteriorly and to some extent posteriorly by small 

 centers, the anterior and the posterior fields. The centers are connected 

 by a "suture fibril" which marks the ventral side. The suture fibril is 

 interrupted by the oral region, thus dividing it into pre- and post-oral 

 segments. Concentric accessory suture fibrils lie on the sides of the oral 

 region and terminate anteriorly and posteriorly in the suture fbrils. The 

 lip of the oral opening is bounded by ( 1 ) the outer peristomal fibrils, 

 which are also linked to the suture fibril. (2) Circular fibrils line the 

 walls of the oral cavity and radial fibrils intersect the two sets of fibrils 

 at right angles. These transverse connections between the ciliary fibrils 

 are present only in the oral region. 



Two heavy basophilic rods, each attached to a heavy esophageal fibril 

 are located near the esophageal plug. An inner peristomal fibril runs from 

 this bilobed neuromotorium to the basal granules. 



Ciliary rootlets are developed in the region of the inner peristomal 

 fibrils; they are less well developed in the region of the outer peristomal 

 fibrils, and not found in the region of ordinary body cilia. About 50-100 

 individual ciliary rootlets combine to form numerous esophageal strands. 



