43 



Some organs useful, however slightly de- 

 veloped. 



Change of function. 



Correlation of variations. 



(7) Difficulty of explaining electric organ in 



skate. 



An isolated case that probably will be ex- 

 plained with increased knowledge. 



(8) Uselessness of many specific characters. 



(9) Cross infertility between species cannot be 



due to natural selection. 



(10) Free intercrossing renders divergent evolu- 

 tion impossible. 



The last three not valid objections unless 

 natural selection is regarded as the sole 

 factor of organic evolution. 



iv. Panmixia and the Reversal of Selection. 



(Lloyd Morgan, Animal Life and Intelligence, pp. 189-197; 

 Darwin, Origin of Species, Vol. i, pp. 182-183, and Vol. 2, 

 pp. 255-263, Amer. Ed. pp. 149-151 and 404-410; Weis- 

 MANN, Retrogressive Development in Nature, Essays upon 

 Heredity, Vol. 2, pp. 3-30; Romanes and Lankester, Let- 

 ters in Nature, Vol. 41, pp. 437-486, 511, 558, and 584, and 

 Vol. 42, pp. 5, 52, and 79; Romanes, Darwin and after Dar- 

 win, Vol. 2, pp. 291-306; Weismann, Germinal Selection, 

 1896.) 



Dwindling and disappearance of organs during phy- 

 logeny. 



Inadequacy of the inheritance of the effects of dis- 

 use as an explanation. 



Loss of parts in flowers. 



Loss of protective structures in animals. 



Loss of wings in neuter insects. 



L I B R A R Yi3o| 



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