NUCLEI ANT) KTXETIC ELEMENTS 



105 



Collin (1909) and P>ntz (1909) record some observations which 

 suggest their derivation from nuclei (Entz) or at least some connec- 

 tion with them (Collin). A single basal body gives rise to a single 

 cilium (Fig. 54) but groups of them are found at the bases of the 

 more complicated membranes, membranelles and cirri the number 

 varying with the species. Thus INIaier describes 2 in the mem- 

 branelles of Nyctotheriis cordiformis and many of them arranged in 

 a row in the membranelle of Stentor niger; in undulating mem- 

 branes of the vorticellids Maier and Schroder describe 3 rows of 

 basal granules while in the "paroral" and "endoral" membranes 

 of Glaucoma scintiUans there are 5 and 10 rows of basal granules 



a 



Fig. 54. — Cilia and myonemes of Infusoria, a. Membrane and periplast of Sten- 

 tor coeruleus; b, c, and e, rows of cilia of same; d, myoneme of same; /, optical section 

 of membrane and myonemes of same, and g, optical section of cortex of Holophrya 

 discolor, (o, b, e, after Johnson; c, d, f, and g, after Blitschli.) 



respectively (Maier). In the cirri of StylonycJria histrio which are 

 circular in cross-section, according to Maier, there is a discoidal 

 plate of basal bodies. Alverdes (1922) found that an isolated cilium 

 will beat if the basal body is attached, not otherwise. 



Myonemes.— One of the most striking characteristics of certain 

 types of ciliates is their power of contraction. A fully-expanded 

 Sjnrostornum amhiguiim may be 2 mm. in length but, on irritation, 

 it suddenly contracts to one-quarter that size, or a Trachelocerca 

 jjhoenicopterus contracts to one-twelfth its original length (Lebedew); 

 a FoUicuIina ampulla with its great peristomial lobes widely out- 

 spread quickly folds itself completely into its comparatively narrow 

 tube (Figs. 84, 165), or an entire colony of widely distended indi- 



