56 THE BIOLOGY OF STENTOR 



but on fixing the animals always contracted, as if the myonemes 

 were then being stimulated directly by the fixing agent. 



Simultaneously, Gelei (1926) found the ribbon bundle exterior 

 to the *'endomyonemes" and described it quite accurately within 

 the limits of light microscopy. Identical in location to the so-called 

 neurophane or neuroid, he regarded this fibrous band as giving 

 support and attachment to the myonemes, therefore ''skeletal" 

 in function. 



(e) The cilia 



Cilia comprising the oral membranelles are evidently not only 

 longer but also of larger diameter than the body ciha, according 

 to Randall and Jackson. They found that the body cilia oi poly- 

 morphus measured 20 /x in length, while in light microscopy they 

 appear to be 10 /x (Andrews, 1945, found them to be 13 /x in coeruleus). 

 This discrepancy may be due in large part to the fact that the cilia 

 have very fine tips, not easily visible. Thus, in a pioneer work of 

 Schuberg (1905) on coeruleus cilia stained by the Golgi method it 

 was shown that the proximal two-thirds of the cilium stains darker 

 and is of uniform diameter, the distal third being much narrower 

 and pointed at the end. Because the freed ciha were curved, he 

 foretold the view now generally held, that the contraction of the 

 cilium is intrinsic. He also noted that fixation seems to preserve 

 the cilia in phases of their rhythmic beating, thus anticipating the 

 interesting work of Parducz (1953). This general picture was con- 

 firmed with the electron microscope by Randall and Jackson whose 

 figures also show that the fine tip is prolonged into the length of 

 the wider portion as its axis. 



Randall and Jackson unmistakably show that at the posterior end 

 of the cell the body cilia are paired and no longer form a single 

 row, raising the question of how in division the proter, acquiring 

 a new posterior end out of the middle parts of the cell, could 

 develop a double row. Possibly there is new growth there, as 

 Johnson first suggested. 



Electron microscopy reveals in stentors the universal fine struc- 

 ture of the cilium. The outer layer is continuous with the pellicle 

 and the axis shows the typical 9 + 2 fibers (Faure-Fremiet and 

 Rouiller, 1955; Randall and Jackson, 1958). A characteristic 

 septum or basal plaque was found at the level of the cell surface 



