PULPS AND SACS OF THE HUMAN TEETH. 



9 



Fig. 10. 



5. In an embryo of the tenth week the following ap- 

 pearances presented themselves : 



Upper Jaw. Very little change had taken place in the 

 lateral lobules (n, Fig. 10), or 

 the median (m) and its additional 

 lobule (y). They had all increased 

 absolutely, and if any relative change 

 had taken place, it was in the trans- . 

 verse diminution of the median (m) 

 and the movement forward of its 

 additional lobule (y). The palate 

 had advanced anteriorly, so as not 

 only to have encroached in some de- 

 gree upon the median and lateral lobule, but also to have 

 thrown itself into folds immediately behind them. The outline 

 of the horse-shoe lobe (which is represented in the sketch as 

 turned aside to exhibit the dental groove), was still observed. 

 There was an indistinct uvula. The papillae (1 and 2) had 

 sunk completely into follicles, and could only be seen by 

 looking into the open mouths of the latter. The mouth of 

 (1) was bordered by four laminae or lids, that of (2), by three, 

 as represented in the sketch. The papillae (3 and 4) had not 

 increased much, but their notched laminae had become more 

 distinct. At the posterior extremity of the 

 floor of the dental groove, on the inner side 

 of the lobule (q, Figs. 4, 6, 8, 10), a slight 

 bulging (5, Fig. 10) was seen. 



The upper lip had receded in the neigh- 

 bourhood of the median line, so as to have 

 U disappeared almost entirely at that spot, 

 the centre of the upper dental arch being 

 Fig. n. exposed. 



Lotver Jaw. The bulgings on each side of the median line 

 (3, 4, Fig. 11), which were so indistinct in the last subject, 



