ROOT STRUCTURES 



63 



the kinetodesmal fibres may run straight, or may spiral around one 

 another (Ehret and Powers, 1959). 



A very similar kinety structure has been found in tetrahymenid 

 ciliates by Pitelka (1961), although the kinetodesmal fibres may be 

 much shorter (Fig. 14). In Tetrahymena for example, each 

 kinetodesmal fibre overlaps the fibre in front by only about one- 

 third of its length, so that transverse sections never show more 



Fig. 14. Diagram of the surface view of parts of two kinetics 

 of Colpidium campylum. The larger circles represent the ciliary 

 basal bodies (kinetosomes) with associated parasomal sacs 

 (smaller circles). In the kinety on the left the striated kineto- 

 desmal fibrils are shown, and in the kinety on the right the 

 unstriated longitudinal, transverse and postciliary fibrils are 

 shown ; both occur in all kinetics of the organism (from Pitelka, 



1961). 



than two kinetodesmal fibres in any kinety; the striated fibres 

 again taper from about 1200 A to a point (Metz and Westfall, 1954). 



The kinetodesmata of the astome ciliate Metaradiophrya gigas 

 are composed of characteristic striated fibres, with a period of 

 about 500 A, which reach a much larger diameter of up to 0*5 to 

 0*9 )Lt, especially near their insertion on the attachment organ of 

 this parasite (de Puytorac, 1959). 



These kinetodesmata built up of tapered striated fibres are 

 generally thought to be homologous with the " kinetodesmata " 



