THE DEVELOPMENT OF THE JAW. 177 



a slight osseous jaw outside Meckel's cartilage, which is not 

 however in any way implicated in it, and very soon begins 

 to waste away, so that by the end of the sixth month it has 

 disappeared : that end of it alone which extended up to the 

 tympanum does not so waste away, but becomes ossified into 

 the malleus. There are, however, observers who hold that 

 in some animals, at all events, Meckel's cartilage plays a 

 more active part in ossification of the jaw. 



In the upper jaw the suture separating the intermaxillary 

 from the maxillary bones becomes obliterated very early on 

 the exterior surface, but it long remains distinguishable on 

 the palatine aspect of the bones. 



The later changes which are undergone by the jaws during 

 the development, eruption, and loss of the teeth, have long 

 engaged the attention of anatomists, and amongst others of 

 Hunter, who was the first to arrive at a tolerably correct 

 appreciation of the process. In the first edition of my 

 father's " Dental Surgery," the results of a very extensive 

 series of observations carried out upon maxillae collected by 

 himself, were detailed, confirming in the main Hunter's 

 conclusions, but adding many new points to our knowledge ; 

 and from this work I have borrowed largely in the present 

 chapter. Professor Humphrey, who had overlooked these 

 descriptions, which were never published in any other form 

 than as an introduction to the " Dental Surgery," instituted 

 a series of experiments upon growing animals, which tended 

 towards the same conclusions. 



As a means of giving the student a guide in his reading 

 of the following pages, and a clue to the results towards 

 which he is being led, a preliminary statement, which does 

 not pretend to scientific accuracy, may perhaps be useful ; 

 while the description given will relate for the most part to 

 the lower jaw, because its isolated position, bringing it into 

 relation with fewer other bones, renders it more easy to 

 study; not that any difference of principle underlies the 



