of the Vertebrate Skeleton. 273 



kind of evidence is, it gives but a poor idea of the potency of 

 this power to produce growth when circumstances are specially 

 favourable. 



In the case of muscles, the most wonderful example is 

 afforded by the increase of the uterus in the exercise of its 

 function, and its rapid degeneration when that function is 

 completed. 



In the case of bones, an example no less wonderful as an 

 increase, but not so obviously due to a local function as to 

 an hereditary condition of the body, is afforded by the antlers 

 of the male deer ; and no more striking example could be 

 afforded of the dependence of growth upon nutrition, which 

 tinder other circumstances these mechanical actions increase, 

 than is seen in Hunter's experiment, the transplantation of 

 the spur of the cock to its comb, where the spur grows vigo- 

 rously, and in one case has attained, in a spiral form, a length 

 of 6 inches. 



These and such like considerations have not escaped the 

 attention of some of the greatest physiologists and best ob- 

 servers of the body in health and disease, and have led them 

 to advance, on inductive evidence, views of growth identical 

 with those which are here urged deductively. Thus Sir James 

 Paget finds that growth is due to intermittent pressure, which 

 approximates the state of the tissue towards that of inflam- 

 mation, but does not actually in healthy growth reach the 

 inflammatory state. 



In the last instances adduced, examples have been given of 

 the result of altered nutrition upon growth, where that altera- 

 tion was not due to mechanical action. Now we may notice 

 some individual cases in which the dialyzing action called 

 nutrition becomes altered abnormally, and parts change their 

 characters so as to present in the individuals of a species pro- 

 cesses similar to those which are normal in comparative ana- 

 tomy. In some of its aspects pathology might be called an 

 inverted pala3ontology. 



Thus Sir J. Paget concludes that " when any of the long 

 bones of a person who has not yet attained full stature is the 

 seat of disease attended Avith unnatural flow of blood in or 

 near it, it may become longer than the other or more healthy 

 bone." And in one case where one segment of a leg Avas de- 

 fective in growth, another segment lengthened to supply the 

 deficiency. But the examples of hypertrophy of bones from 

 disease are not numerous ; and in rickets only an inflamma- 

 tory thickening of the bones takes place. Still the cases are 

 many in which increased osseous growth takes place in con- 

 sequence of the inflammatory condition induced by fractures. 



