SOCIETY OP THE UNIVERSITY OF ABERDEEN. 01 



4. The condf/loid centre, which will form the condyle and part of 



the ramus. 



5. The coronoid centre, giving rise to the coronoid process and 



the part of the ramus which forms its base. 



6. Lastly, the splenial centre of Spix, situated on the inner face of 



the bone and extending from the orifice of the future dental 



canal to the incisive piece. 



For a number of years I have worked at the development of the 

 lower jaw in man and mammals. In the present paper I review the 

 literature of lower jaw development and then record the results of 

 my own researches regarding the development of the lower jaw in 

 man. 



REVIEW OF LITERATURE. 



There is an extensive literature on the subject of lower jaw 

 development, giving the results of research done, especially by workers 

 abroad. In recent work some of these researches seem to have been 

 overlooked, and hence I propose to review briefly the work done on 

 and views held regarding the development of the lower jaw in man 

 and mammals. 



Spix (18), in 1815, in his Cephalogeneais, described the lower jaw 

 as arising from five separate centres, -viz., for the body, condyle, 

 coronoid, angle and the " piece of Spix " or splenial this last, he says, 

 remains as a separate piece up to the fourth month of foetal life. 



Meckel (13), in 1820, described the cartilage of the lower jaw 

 hence " Meckel's cartilage ". He denies the presence of a separate 

 splenial element. He says that one or two ossicles may be found at 

 the symphysis between the two halves of the mandible. 



Magitot and Robin (10), in 1802, gave a detailed description of 

 Meckel's cartilage in man. They hold that it takes no part in lower 

 jaw formation, and that after the sixth month of foetal life the car- 

 tilage atrophies, the malleus being the only part which persists. 



Rambaud and Renault (16), 1864, described the lower jaw as 

 arising from six centres, visible at the beginning of the eighth week. 



