PULPS AND SACS OF THE HUMAN TEETH. 17 



incnt of the external spongy membrane from the posterior 

 group showed, wliat was not at first ohser\'ed, that there was 

 at the posterior part of the posterior sac another very small 

 one, which by careful examination was seen to be the fundus 

 of the open follicle in the non-adherent portion of the dental 

 groove. 



The adhesion of the lip and walls of the groove had now 

 become so strong, that it was impossible to separate tliem. 

 The only way, therefore, in wliich its contents could be 

 examined was by transverse sections. When these sections 

 were made between the different sacs, they displayed scarcely 

 any traces of the dental groove ; but when they passed througli 

 any place perpendicular to the surface of the gum, and near to 

 the middle of any of the sacs, they exhibited the appearances 

 represented in the marginal sketch (Fig. 20). The deciduous 

 tooth pulp (a), which was lately a free pa- 

 pilla ; (b), the section of its sac, which was ^, 

 a follicle when the pulp was a papilla ; (rf), 

 the line of adhesion of part of the walls 

 of the dental groove leading from the shut ^'^- -"■ 



sac to (c), the raphe of the groove ; (c), the section of the 

 non-adherent portion of the groove in the situation of 

 the lunula, wliich existed behind (/), the inner laminte 

 of the sac (h), in its former follicular condition. From the 

 consideration of this section (Fig. 20), the mode in whicli 

 the original follicle, the non-adherent depression behind 

 the inner laminaj, and the walls of the dental groove, were 

 connected after fuU adhesion of all the neiglibouring parts, 

 will be easily understood. The little cavity (e) adhered by 

 its anterior and inferior extremity to the line of adhesion 

 (d), so that it and the sac of the milk-tooth were both con- 

 nected to the raphe of the edges of the dental grooves by lines 

 of attachment, whicli resembled two petioles proceeding from 

 a common footstalk. These lines of attachment were not 



