NUCLEI AND KINETIC ELEMENTS 109 



cell to the posterior end. Cilia in the same transverse row beat 

 synchronously, but each cilium in a lonjjituflinal row begins its 

 beat shortly after the cilium anterior to it has started and before it 

 has ended its beat (Verworn). The cilia of transverse rows are thus 

 synchronous, those of longitudinal rows metachronous in their con- 

 tractions, a phenomenon which accounts for the wave-like movement 

 of imdulating membranes which are formed of fused cilia of longi- 

 tudinal rows (well shown in the undulating membranes of the 

 Vorticellidie). According to Alverdes (1922) isolated cilia with 

 basal body may act independently of a coordinating system but 

 they do not react to stimuli. 



This regularity of cilia movement which may be easily seen in 

 the uniform ciliar\' coating of Ni/ciothcnis ovaJis from the cockroach, 

 indicates the transmission of impulses and the activity of some coor- 

 dinating mechanism in the cell. Entz, Maier, Schuberg and many 

 other observers, have found distinct fibers connecting the basal 

 bodies of Protozoon cilia and have generally interpreted them as 

 myonemes. Since forms like Nyctothcrus, Frontonia, Paramecium, 

 etc., which do not contract, show the same rhythmical action of the 

 cilia, it is probable that the threads connecting their basal bodies are 

 not myonemes but coordinating fibrils (Fig. 57). It is conceivable, 

 moreo\'er, that m\onemes in a generalized condition may be both 

 coordinating and contractile in function. In some cases, however, 

 two distinct sets of fibrils have been observed, one of which is 

 interpreted as contractile, the other as conductile. Thus Xeres- 

 heimer described "myophanes" and "neurophanes" in Stcntor 

 coeruh'us, and CUviacostomum lirens, the former extending the entire 

 length of the body, the latter only from the base to the center (Fig. 

 56). On a priori grounds, it would seem that, as Yocom points out, 

 Neresheimer made an unfortunate application of his two terms, 

 his neurophane fibers, for example, to which he ascribes a trans- 

 mitting function, being situated in the least advantageous position 

 for the f mictions of irritability or conductility, Jennings having 

 shown that the first and most strongly marked reactions to certain 

 stimuli in ciliates appears in the anterior region, a result confirmed 

 by Alverdes (1922). 



The more recent obser\ations of Sharp, Yocom, and Taylor, all 

 from Kofoid's laboratory, af^'ord more striking evidence of specific 

 conducting or coordinating fibrils in ciliates. In connection with 

 Diplodiniiim ecavdahnn , Sharp described, for the first time in the 

 literature, a system of connected fibrils emanating from a common 

 mass of difterentiated protoplasm, which he called a "motorium," 

 the whole system being termed the "neuromotor apparatus." 

 The motorium is situated in the ectoplasm of the anterior end of 

 the organism between the two zones (adoral and dorsal) of mem- 

 branelles (Fig. 2, p. 20, and Fig. 57) . From it as a center a number of 



