LIST OF ILLUSTRATIONS xvii 



FIG. PAGE 



60. Reconstructions of evolutionary stages in the evo- 



lution OF THE HORSE SKULL, BY THE METHOD OF CAR- 

 TESIAN TRANSFORMATION ; AND COMPARISON WITH 

 ACTUAL FOSSIL SKULLS . . . . . log 



{From D'Arcy Thompson, 1917) 



61. Growth-gradients along the body- axis of the hermit 



crab eupagurus . . . . . . .112 



{From Bush, 1930) 



62. Growth-intensities of various parts in male and 



female Stag-beetles (Lucanus) . . . .114 



63. Growth-gradients of male and female stag-beetles 115 



64. Growth-profile of metamorphosing herring . .116 



{From Huxley, 1931B) 



65. Effect of a region of high growth-intensity on 



growth of neighbouring parts in spider-crabs 

 (Maia and Inachus) ...... 122 



{A, from Huxley, 1927 a ; B, from Shaw, 1928) 



66. Effect of a region of high growth-intensity on 



growth of neighbouring parts in prawns (Palae- 

 mon) . . . . . . . . .124 



{A, from Shaw, 1928 ; B, from Tazelaar, 1930) 



67. Relative growth of parts anterior and posterior to 



a region of high growth-intensity in prawns 

 (Palaemon) ........ 125 



{From Tazelaar, 1930) 



68. Effects of a regenerating limb upon the growth of 



neighbouring limbs in Sphodromantis . . . 127 



69. Graded growth-effects in two human monsters . 130 



{A, from Nanagas, 1925 ; B, from Mead, 1930) 



70. Change in relative weight of various organs of the 



cat during fetal life . . . . . -134 



{After Latimer and Aikman, 1931) 



71. Positive heterogony of head-length in whalebone 



WHALES ......... 137 



72. Changes in relative weight of various organs of the 



chick during embryonic life .... i43 



{After Schmalhausen, 192713) 



73. Growth-rates of various organs of the chick during 



embryonic life ...... i44-i45 



74. Diagram illustrating the co-operation of two 



growth-ratios in determining the form of mol- 

 luscan shells . . . . . . 1 56 



75. Origin of the spiral form of the shell in Limacina . 159 



{From original by Dr. Lebour) 



76. Diagram of the growth-gradients operating to pro- 



duce THE TURBINATE SPIRAL SHELL OF MOLLUSCS . l6o 



77. Heterogony of normal and regenerating claws in 



portunus ........ 166 



78. Asymmetry in the thoracic ganglia of the male fid- 



dler-crab ........ 168 



{From Ratcliffe, unpublished) 



79. Chemical and metabolic gradients in Crustacea and 



earthworms . . . . . . . .170 



{From Perkins, 1929) 



