STUDIES ON ISOLATED FLAGELLA 271 



selves may be a bit hard to believe. Unfortunately a satisfactory 

 photographic demonstration of this swimming is still not available. 

 However, wave propagation, which is the prerequisite for forward pro- 

 gression, can be demonstrated with simpler photographic equipment, 

 and this is being attempted. Preliminary results, sampled in Fig. 1, 

 are technically of low quality, but nevertheless show that the beating 

 does not have a standing wave pattern, but is propagated along the 

 flagellum. 



In general, the beating of the reactivated isolated flagella appears 

 qualitatively similar to that of normal flagella. It shows the three 

 features of normal beating — wave propagation, rotation, and for- 

 ward progression — commonly absent in reactivated mammalian sper- 

 matozoa (Bishop and Hoffmann-Berling, 1959), possibly because a 

 relatively mild "extraction" technique is satisfactory with these thin 

 flagella. 



Quantitatively, the degree of bending of the isolated flagella is 

 less than normal. The amplitude of 2 to 3 microns is perhaps about 

 one-half the normal amplitude, and the wavelength is greater than 

 normal. The swimming speed of isolated flagella varies around 10 

 microns /sec, compared with a swimming speed of 40 to 50 microns/ 

 sec for normal cells at the same temperature. A rough calculation of 

 the energy required to sustain the beating of isolated flagella, by 

 using the equations of Taylor (1952), indicates that only about 5% 

 of the energy available from dephosphorylation of ATP is being con 

 verted to movement against the viscous resistance of the medium. 

 Most of the available energy would be needed to sustain the beating 

 of flagella of normal cells. 



Two possible interpretations of the apparent inefficiency of re- 

 activated isolated flagella come to mind. The flagella may be ab- 

 normally stiff, on account of the preparative treatment, so that en- 

 ergy is required to overcome the internal resistance of the flagella 

 as well as the viscosity of the medium. On the other hand, there may 

 be a partial uncoupling between ATP dephosphorylation and move- 

 ment, so that only a part of the available chemical energy can be 

 transformed into mechanical work. The viscosity of the medium 

 should have a relatively small effect on movement in the first case, 

 and a much larger effect in the second case. Some results of experi- 

 ments with media of increased viscosity are shown in Fig. 2. 



The swimming speed of normal cells of Polytoma uvella was meas- 



