228 FREDERICK G. E. PAUTARD 



"muscle." To do this, the random systems had to be ordered and made 

 stable. But what of these random systems? Perhaps these were the re- 

 sult of a much longer evolution of unstable "globular" molecules, 

 which in themselves possess a kind of molecular predation. Indeed, 

 the flagellum itself might be an early attempt at peaceful coexistence 

 after a long period of bitter struggle between rival contestants. 



Acknowledgments. I wish to record my thanks to all those who have 

 helped to supply fresh fish sperm during this research. In particular, the 

 active cooperation of Mr. G. Tatham, of the Welham Park Fish Hatchery, 

 Malton, has been greatly appreciated, as also has been the help given by 

 the Freshwater Biological Research Association, Lake Windermere, 

 through the interest of the Director, Mr. H. Cary Gilson, F.R.S., and Mr. 

 G. Thompson and his staff. 



My colleagues have assisted on numerous occasions, and I am especially 

 grateful to Dr. G. N. Graham for preparations of actin and much fruitful 

 biochemical discussion, to Dr. K. D. Parker for infrared absorption data, 

 to Dr. E. Beighton for the low-angle x-ray diffraction pattern reproduced 

 in Fig. 4b, to Dr. K. M. Rudall for much valuable information, and to 

 Mr. A. Millard for the electron micrographs reproduced in Figs. 1, 2, 6a 

 and c. I am indebted, above all, to the late Professor W. T. Astbury, for 

 his stimulating encouragement and criticism throughout this work. 



This research was commenced during the tenure of an I.C.I. Fellowship, 

 and has been continued with support from the Muscular Dystrophy As- 

 sociation of America Inc. 



REFERENCES 



Afzelius, B. 1959. Electron microscopy of the sperm tail: Results obtained 

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Astbury, W. T. 1947a. On the structure of biological fibres and the prob- 

 lem of muscle. Proc. Roy. Soc. (London), B134, 303-328. 



Astbury, W. T. 1947b. X-ray study of actin. Nature, 160, 388-389. 



Astbury, W. T. 1958. Macromolecules: introduction. Discussions Faraday 

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Astbury, W. T. 1960. Indications on muscle contraction from x-ray dif- 

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Astbury, W. T., E. Beighton, and C. Weibull. 1955. The structure of bac- 

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