STUDIES ON ISOLATED FLAGELLA 



275 



20 40 60 80 100 

 VISCOSITY (centipoises) 



Fig. 4. Effect of viscosity on beat frequency (/) at ATP concentrations 

 of 1 X 10-W (©), 3 X 10- W © and 5 X 10" 4 M (Q). 



phorylation is independent of ATP concentration in this range, there 

 is apparently a change in the efficiency of utilization of chemical en- 

 ergy provided by ATP dephosphorylation. 



The work involving stroboscopic measurement of beat frequency 

 was begun only recently, and only these few results have been ob- 

 tained thus far. It is certainly premature to attempt to use them to 

 test any theories of flagellar activity, but some discussion of theory is 

 appropriate here. If we assume that some portions of flagella must 

 convert chemical energy of ATP into mechanical work as expressed 

 by active contraction, the remaining basic question is: How is the 

 rhythmic, propagated contraction of flagella coordinated, even after 

 isolation and treatments which are supposed to disrupt completely 

 membrane permeability? One possible explanation has been sug- 

 gested by the work of Boettiger, Pringle, and others on the rhythmic 

 activity of insect fibrillar muscle (Pringle, 1957; Machin, 1958). 



These muscles maintain oscillations at a frequency which is de- 

 termined not by the frequency of membrane excitation, but by the 

 mass and elasticity of the mechanically oscillatory system to which 

 they are coupled. The amplitude of oscillation is determined by the 

 resistive load on the system. The contractile element in the muscle 

 can act as the equivalent of a negative resistance element, to supply 

 power dissipated in the resistive load as the mechanical system oscil- 



