254 DAVID W. BISHOP 



tion of permeability and ionic balance was further indicated by 

 failure of wave propagation along the flagellum and a consequent lack 

 of forward progression of the reactivated cells (Bishop and Hoffmann- 

 Berling, 1959). In the latter respect, sperm models differ, perhaps as 

 a result of more complete extraction, from the models of Polytoma 

 flagella discussed by Brokaw elsewhere in this symposium. 



The salient and truly spectacular feature of sperm model reactiva- 

 tion is the fact that the addition of "physiological" amounts of ATP 

 to the system initiates rhythmic wave formation which in bull sperm 

 models may persist for two hours or more. This is in striking con- 

 trast to muscle models which ordinarily, upon the addition of ATP, 

 shorten once and remain in a contracted state until external condi- 

 tions are altered. In flagellar models both contractile and relaxation 

 phases — the "shortening" and "elongation" processes — of the bend- 

 ing cycle are set in motion by ATP, and the perpetuation of the 

 rhythm suggests an oscillating mechanism rather than a simple con- 

 traction-relaxation system. 



Both amplitude and frequency of beat following reactivation prove 

 to be in many, if not most, preparations quite comparable to that of 

 live sperm. The ATP-induced bending wave of bull sperm, for ex- 

 ample, shows a maximal amplitude of about 10 microns, approxi- 

 mately twenty times the tail diameter and far exceeding that which 

 might be anticipated if nonspecific forces such as Bronwnian move- 

 ment were responsible for motility. Moreover, the shape of the in- 

 duced waves compares favorably with the major uniplanar bending 

 cycles of normal sperm in that both sides of the flagellum are active 

 and capable of what appears to be contraction. Wave formation may 

 occur throughout the flagellum, or be limited to a restricted proxi- 

 mal and/or distal segment; there is no indication in the sperm models 

 that wave formation begins at the base and is propagated toward the 

 tip of the flagellum. Three-dimensional wave motion is apparently 

 absent and thus there is no helical movement or rotation along the 

 longitudinal axis of the flagellum. 



Whereas the capacity for wave formation is retained by the ex- 

 tracted cells, coordination and wave propagation are completely de- 

 stroyed. Along with this loss, the capacity for forward progression 

 likewise disappears (Hoffmann-Berling, 1955a; Bishop and Hoffman- 

 Berling, 1959). No adjustment of ionic balance has been found which 



