vi CONTENTS. 



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for natural selection, 36. Many specific differences are 

 indifferent, /. e., not adaptive, 38. The extinguishing of 

 the extreme variations by interbreeding, 44. The im- 

 probability of the occurrence of the right variations at the 

 right time, 45. The difficulty of explaining the production 

 by natural selection of specialisations useful only in highly 

 complex condition, 49. The objection based on the over- 

 development of specialisations, 53. The objection based 

 on insufficient time, 54. The objection that natural selec- 

 tion tends to preserve the type rather than the variants, 

 and hence opposes change, 56. 



APPENDIX: Books and papers on variation, 57. Cases of 

 marked variation in parthenogenetic animals, 58. Varia- 

 tion according to the law of probabilities, 59. Quetelet, 

 the discoverer of variation according to the laws of chance, 

 61. Example of trivial variations, 62. Nageli's seven 

 objections to species-forming by selection, 62. Wolff's 

 attack on the selectionists' assumption of the appearance 

 at the right time of the needed variation, 64. Example of 

 non-correlated variability in bilaterally repeated organs, 

 65. Henslow's antagonism to selection as an explainer of 

 floral correlations, 67. Wolff's objection to the necessary 

 assumption of identical and coincident variation in re- 

 peated structures, as feathers, scales, etc., 67. Example 

 of mal-adaption in the egg-laying habit of Phryganidia 

 calif or nica, 68 Pieper's antagonism to the selection ex- 

 planation of colour and pattern in insects, 69. 



CHAPTER IV, 



DARWINISM ATTACKED (Continued} .... 70 



Objection to the exclusively linear or quantitative char- 

 acter of the fluctuating or Darwinian variations, 70. 

 Galton's law of regression, 71. Selection may produce 

 evolution (continuous change) but not species (discontinu- 

 ous series), 73. Pfeffer's objection based on the slowness 

 of species transformation, 75. The difficulty of explaining 

 the sterility of species by selection, 76. Selection cannot 

 explain extreme or complete degeneration of useless parts, 

 77. Objections to the assumed rigour of the struggle for 

 existence and to the actuality of intra-specific or personal 

 selection, 79. Indiscriminate extermination due to the 

 fortune of position and time, 80. The necessity of sexual 



