OTHER FACTORS OP EVOLUTION 127 



and mucous membranes in different parts of the body, and 

 especially the extreme sensitiveness of the finger-tips and of the 

 tongue ; the diminution of the size and weight of the jaws and 

 teeth which characterises the civilised races, as contrasted with the 

 savage races ; and the simultaneous increase in size of the great toe 

 and diminution of the little toe, as the result of a cause " which 

 has been operating ever since the earliest anthropoid creatures 

 began to decrease their life in trees, and increase their life on the 

 earth's surface," the changes being attributable to the fact that 

 " effort is economised and efficiency increased in proportion as the 

 stress is thrown more and more on the inner digits of the 

 foot and less and less on the outer digits." Dr. Havelock 

 Charles has also made known more than twenty differences, 

 chiefly in the structure of the knee and ankle joints, to be 

 met with between the leg-bones of Europeans and those of the 

 Punjaub people — " differences caused by their respective habits of 

 sitting in chairs and squatting on the ground." Markings and 

 facets possessed by the latter and transmitted by heredity (since 

 they are to be found in the new-born infant and even in the foetus) 

 are present owing to their habit, uniformly persisted in through 

 innumerable generations, of squatting ; while there is a total dis- 

 appearance of the markings in question in the skeleton of the 

 European, " as no advantage would accrue to him from the posses- 

 sion of facets on his bones fitting them for postures not practised 

 by him" {loc. cit. I, p. 689). 



These points noted by H. Chai-les are, however, only special 

 instances of what had previously been established by Cope. He 

 says {loc. cit. p. 467) : — " all the form characters of the vertebrate 

 skeleton, and for that matter, of the hard parts of all animals, have 

 been produced by muscular pressures and contractions, and the 

 friction, strains, and impacts due to these . . . the characters of 

 the skeleton can generally be shown to be inherited, because they 

 appear before birth, and are found at some stage or another of 

 foetal life." And elsewhere (p. 9) he says : — " By the discovery of 

 the paleontologic succession of modifications of the articulations 

 of the vertebrate, and especially mammalian skeleton, I first fur- 

 nished an actual demonstration of the reaUty of the Lamarckian 

 factor of use or motion, as friction, impact, and strain, as an efficient 

 cause of evolution." He believes this kind of evidence to be also 

 particularly strong in regard to the formation of the segments of 

 the body and limbs of the Arthropoda (p. 404). 



