ESSAYS 



RESPECTING THE CHANGES WHICH THE 



HUMAN SKELETON 



UNDERGOES AT 



DIFFERENT PERIODS OF LIFE ; 



AND THE DEFORMITIES TO WHICH IT IS SUBJECT DURING ITS DEVELOPMENT. 



By WILLIAM WALLACE, M. R. C. S. I. M. R. L A. 



LECTURER ON ANATOMY AND SURGERY, ONE OF THE SURGEONS TO THE 



CHARITABLE INFIRMARY, AND SURGEON TO THE DUBLIN INFIRMARY 



FOR CURING DISEASES OF THE SKIN. 



ESSAY I. 



When we take a general view of the organization of animals, 

 we remark great variety of structure. Every class possesses organs 

 peculiar to itself; and the organs, which each class enjoys in com- 

 mon with others, are subjected to numerous modifications. Hence, 

 those characters are very few, which are common to the different 

 classes of animals, or to the same kind of organ in different ani- 

 mals. Their resemblance often consists in little more than in the 

 effect produced. To ascertain these varieties and their laws, at the 



VOL. XIII. T 



