LIST OF ILLUSTRATIONS xix 



FIG. PAGE 



98. Diagram showing the effect of rate-genes on eye- 



pigmentation in Gammarus ..... 228 

 (From Wells, Huxley and Wells, 'The Science of Life,' London, 

 1931) 



99. Rate of eye-darkening in two genetic strains of 



Gammarus ........ 230 



(From Ford and Huxley, 192Q) 



100. Effect of rate of general growth on rate of eye- 



darkening IN A PURE STRAIN OF GAMMARUS . . 230 



(From Ford and Huxley, 1920) 



101. Multimodal frequency-distribution of body-build 



index in man ........ 233 



(From Davenport, 1923) 



102. Diagram illustrating the effect of rate-genes upon 



vestigial organs ....... 236 



103. Effect of temperature on rate of eye-darkening in 



a pure strain of gammarus ..... 238 

 (From Ford and Huxley, 1929) 



104. Diagram illustrating the relation of mutations in 



rate-genes to recapitulation and paedomorphosis 24o 



