PRESENT PROI5LEMS IN EVOLrTION AND HEREDITY. 345 



(*;il)8ulai' lipinieiit:" tlu' Iclt half of the axis was united by 1)()ih' to 

 tlic (•()n-(^s])()ndin,ii' portion ot'th*^ third ('crvical: tlioi-e was found a 

 new u[)\vai'd prolon.iiation of the (xUmtoid peg <»f tlie axis, and a new 

 accessory transverse li,i>anu'nt to keep it from pressing- upon tiie cord. 

 In short, " the anatomy of the shoemaker represents the fixation and 

 snl)se<|uent exaggeration of tlu' i)osition and tendencies to cliange 

 wliicli were pi'esent in his body when In- assnnn^d tlic ])osition toi' a 

 sliort period of time. 



Rate of inlieritance. — This illustiation serves als(» to emphasize the 

 great contrast between the rapidity of individual transformation and 

 the slowness of race transformation. No one would expect the son of 

 this shoemaker to exhibit any of these acciuired malformations. Vet 

 I )i'. Lane thinks he lias observed such effects in the third generation 

 })}' the summation of similar influences. 



All pahcontological evidence goes to show that the effects of ncMinal 

 habits, if transmitted at all, wonld l)c entirely im})erceptiblc in one 

 generation. The horse, for example, has not yet completely lost the 

 lateral toes which became useless at the end of the l"i)per Eocene ])eriod. 

 This objection as to rate of evohition may ])e nrged with equal force 

 against the natural selection theory. It is obvious thatthe activepro- 

 gressive principle in evolution (whatever it is), must contend with the 

 ciiormons conservative power of inheritance, and this, to my mind, is 

 one of the strongest arguments against the possibilities of the rise of 

 adapt i\e organs by the selection of chance favorable variations in the 

 germ plasm. 



Apj)lication to human eroliifioii. — Principles underlying these illus- 

 trations may now be applied to some of the facts in human evolution 

 brimght out in the first lecture. They show that if functional tenden 

 <Mes aie transmitted we can comprehend the distinct evolution history 

 of each organ; the rise and fall of two organs side by side; the delinitc 

 and purposixe character of some anomalies; the increase of vai'iabilit\ 

 in tiu' regions of most rapid evolution; the correlation of de\"clo])nn'nt 

 balance, and degeneration in the separate organs of the shouldei', hand, 

 and foot. 



Vet even granting this theory there still remain ditfu'ultics. Tlie 

 relation of use and disuse to some of the contemporary changes in the 

 human backbone is lather obscure. 1 would hesitate to jnonounce an 

 opinion as to whether our present habits of life are tending to shorten 

 thclninbars, incrcuise the spinal curvatures, and shitt the pehis with- 

 out nndcing an exhaustive study of Iiuman motion. Among the inlhi 

 ences which Dr. Lane has suggested* as operative here ai'c the wear- 

 ing of heeled sho(;s and the incr(!ase of the cranium, lie considers the 

 additional or sixth lumbar vertebra as a new element rather than as a 

 reversion, and works out in some detail the mechanical effects of the 



'Journal of An atom >j and Phi/sioloffji, 1888, p. 219. 



