iCL 



- ~ ' 



v - 



A'AA 'A 1 TO GENESIS. 287 



elevated portions remain adjacent to them. Other 

 elevations, as already described, are due to deposit of 

 bone stimulated by the absence of accustomed pres- 

 sure, as in the filling up of the old ulnar cotylus in 

 the human subject above described. Other elevations 

 or osseous deposits such as occur at muscular and 

 ligamentous insertions appear to follow a pulling stress. 



Many other examples of the abnormal production 

 of articulations might be cited, but the above are suf- 

 ficient to show the plasticity of osseous tissue. It is 

 also evident that if such results follow the stimulus of 

 the parts during a short period of months or years, 

 the continuance of the appropriate mechanical stresses 

 through geologic ages must have been quite sufficient 

 to produce all the characters which we observe in the 

 articulations of the vertebrate skeleton. 



I will now present the inferences which may be de- 

 rived from consideration of the facts hitherto presented 

 in this chapter. We have not been witnesses of the 

 process of evolution, yet we believe that it has been 

 in active operation. We have not been able to observe 

 its modus operandi, but we may safely infer what it 

 has been from the facts which are before us. Kineto- 

 genesis having been observed in both the soft sarcode 

 (muscle) and in the hard parts of animals, the law of 

 uniformity obliges us to believe that similar changes 

 have taken place in past ages whenever the necessity 

 arose, and the energy at nature's disposal was suffi- 

 cient. 



ii. MOULDING OF THE ARTICULATIONS. 



a. The Limb Articulations. 



This part of the subject has the advantage of many 

 facts of paleontology in our possession. We have 



