24 General Morphology of the Protozoa 



Infraciliary network 



This system lies at the level of the basal granules or somewhat 

 deeper, between the alveolar and the inner ectoplasmic layers (62). 

 Neither the basal granules nor the trichocysts are directly connected with 

 this system, and no connection with the outer network has been observed. 

 The longitudinal fibrils of the infraciliary system generally follow the 

 pattern of the ciliary rows. 



The infraciliature 



The basal fibril, or kinetodesma, of Chatton's infraciliature is 

 considered to be separate from the ciliary meridian of Klein. The silver- 

 line fibril is said to lie on the left of the basal granules while the 

 kinetodesma lies on the right (26, 29, 214). However, such regularity in 

 position of the silver-line is not apparent in some of Klein's figures, and 

 in ciliates showing "circular fibrils" in the silver-lines, basal granules may 

 lie on the circular fibril or may be enclosed by it (133). 



Sensory bristles 



So-called sensory bristles, apparently associated with the fibrillar 

 systems of certain ciliates, are well developed on the dorsal surface of 

 Euplotes (79, 212). Each bristle arises from a granule at the base of a pit 

 which is surrounded by a "rosette" of rodlets (Fig. 1. 13, F). On the 

 ventral surface, two or three similar rosettes without bristles lie near 

 the base of each cirrus. Analogous structures, supposedly sensory in func- 

 tion, have been described in Didinium and certain other genera (63). 



Significance of fibrillar systems 



According to various workers, the fibrillar systems of ciliates are 

 contractile fibrils, supporting or skeletal structures, organizers in the onto- 

 genetic development of related organelles (134), coordinating systems, 

 and delicate circulatory systems for transporting such materials as nucleo- 

 proteins to the basal granules and trichocysts (86), 



Except for whatever support these hypotheses may derive from mor- 

 phological relationships, the data bearing on functions of fibrillar systems 

 are meager. The results of microdissection suggest a coordinating func- 

 tion in Euplotes (209). The adoral membranelles in this hypotrich are 

 important in swimming, while the anal cirri play a major part in creep- 

 ing. Cutting the membranelle-fibril (Fig. 1. 13, G) destroyed coordination 

 of the membranelles so that swimming movements were abnormal. Sever- 

 ing the fibrils to the anal cirri affected both creeping and swimming, 

 while destruction of the motorium disturbed the coordination of the anal 

 cirri and membranelles. Incisions not severing the neuromotor fibrils 

 failed to modify swimming or creeping movements. Similar experiments 



