16 ON THE ORIGIN AND DEVELOPMENT OF THE 



follicles, and the walls of the groove, were found to be rough 

 and flocculent from adhesions, with the exception of the little 

 depressions formerly mentioned, which still retained their ori- 

 ginal appearance. 



Breadth of the superior arch, 5 lines ; length, 4 lines. 



10. Wth week. Upper Jaw. The palate retained the 

 appearance it had in the last subject, with the exception of 

 the median lobule, which had become narrow in front, and 

 broad posteriorly. The raphe of the dental groove had become 

 firmer, so as to give a much more defined and permanent ap- 

 pearance to the non-adherent portion posteriorly, which was 

 now seen to great advantage, its fine greyish mucous mem- 

 brane gradually running at its edges into the white tough 

 substance of the palate and gums. 



Having separated the lips of the non-adherent portion 

 (a, Fig. 19), a papilla, sunk in an open fol- 

 licle, with three or four laminae, was visible 

 (6). The membrane of the palate and max- 

 illary arch being stripped from the bone, and 

 its surface of adhesion examined, lines cor- 

 responding with the .sutures of the bones were observed ; one 

 the median, another the intermaxillary, and a third with the 

 palato-maxillary. Five tooth-sacs were also observed on both 

 sides of the maxillary arch. These were divided into three 

 groups, two in the first or anterior, one in the second, and two 

 in the third or posterior. These groups were covered with a 

 flocculent spongy membrane, which was easily stripped off by 

 the forceps, and when this was carefully done, it became evident 

 that the sacs which were formerly grouped together by this 

 membrane were individually isolated, and formed of a thin 

 grey diaphanous membrane, similar to the one formerly men- 

 tioned as covering the bottom of the dental groove, and con- 

 stituting the membrane of the follicles. The careful detach- 



