ON THE POWER OF THE PERIOSTEUM TO FORM NEW BONE, 15,9 



He carefully investigated the process of ossification during incubation, and detailed 

 the steps of its progress in the chick as well as other young animals. The rudi- 

 ment of the future bone being traced from its earliest distinguishable appearance, 

 was found first to present the characters of a jelly ; then to acquire the consistence 

 of cartilage or gristle ; and finally to reach the perfect osseous state : whence it was 

 contended, that a structure which thus originated in a distinct form, and inde- 

 pendently of any other, could not owe its increase afterwards to a different source. 

 Haller also engaged his pupils Detlef and Boehmer in extensive series of expe- 

 riments, by breaking the bones of animals, and feeding them with madder during 

 then- recovery ; from the results of which he inferred, that Duhamel had been 

 mistaken in supposing that fractures are reunited by ossification of the perios- 

 teum. 



Notwithstanding these objections, and the authority of the physiologist from 

 whom they proceeded, the doctrine of Duhamel still maintained its ground ; and 

 not long afterwards, viz. in the year 1780, derived a great accession of strength 

 from the experiments of Troja, who, by destroying the marrow of bones, caused 

 their death, and the formation of new shells surrounding them, apparently from 

 ossification of the periosteum. This experiment, which Troja himself performed 

 some hundreds of times, when repeated and varied by the pathologists of almost 

 every country, seemed to confirm the ossific power attributed to the periosteum 

 beyond question, until Scarpa, the late distinguished Professor of Pavia, again 

 investigated the grounds on which it was originally founded by Duhamel. In 

 Scarpa's treatise "DePenitiori Ossium Structura," which was published in 1799, 

 he explained, that the foliated appearance presented by bones that had been burnt 

 did not depend upon the development of a structure naturally belonging to them, 

 but was an effect produced by the unequal action of the fire ; and that the se- 

 paration of scales fi*om diseased bones was no stronger proof of their possessing a 

 laminated structure, since thin and broad portions of dead substance are wont to 

 be detached from the skin and other soft textures, in which it was never supposed 

 that layers existed naturally. He recalled attention to the synthetic experiments 

 of Haller, who, by investigating the formation of bone from the earliest stage to 

 its perfect state, had established the reticulated nature of its texture ; and by an 

 opposite process of an analytic kind, which consisted in depriving bones of their 

 eai-thy constituent by means of diluted acids, and then macerating them for a 

 long while in water, he unravelled the texture so as to shew that it really was re- 

 ticular. As a consequence of these observations, Scarpa denied that bone could 

 be formed by the periosteum ; and this opinion was keenly embraced by several 

 pathologists of the present century, and particularly by the French surgeon Le- 

 veille. 



At present, professional opinion is divided in regard to the ossific power of 



