APPENDIX D 231 



physical structure has been immensely modified by it, not by the 

 congenital transmission of acquired characters, but wholly by the 

 transmission and accumulation of such inborn variations as best 

 serve the utilisation of the acquired character ; hence, for instance, 

 the great jaws of F. rufescens. In man occur many examples of 

 physical structures modified by the persistent acquirement in gene- 

 ration after generation, during long ages, of particular acquired 

 characters. For example, his whole digestive apparatus has been 

 modified by his acquired habit of cooking or otherwise modifying 

 his food, to which cause may even be attributed the unsoundness 

 of the teeth of civilised man ; these, since they are no longer 

 absolutely essential to survival, having undergone retrogression 

 as regards their power of resisting bacteria, etc. His lingual 

 muscles have been modified by his acquired habit of speech. 

 His slowly-acquired habit of bipedal progression has resulted in 

 immense and obvious physical alteration. Even the acquirement 

 of surgical knowledge, at first rudimentary, but now highly ad- 

 vanced, has caused at least one important modification. Animals, 

 as a rule, bear their young easily. When any disproportion exists 

 between the fcetal head and the maternal pelvis, both mother and 

 offspring perish, and the peculiarity is not transmitted. Savage 

 women are under much the same conditions, and give birth 

 almost as easily as lower animals. But for ages civilised women 

 in labour have received artificial aid ; they are, therefore, nearly 

 all incapacitated for a time after the birth of each child. Indeed, 

 the recent advance in obstetric science has enabled so many of 

 the otherwise unfit to survive among us for some generations past, 

 that now numerous women are quite unable of parturition without 

 instrumental aid. 



The evolution of the power of acquiring characters, mental 

 and physical, appears to me the most important, indeed the very 

 central, fact in the evolution of all the higher animals. Beyond 

 all other characters this has been steadily evolved by Natural 

 Selection, and, therefore, the higher placed an animal is in the 

 scale of life, the more is the power developed in him. Possibly 

 some other mammals are as capable of acquiring physical char- 



