300 MR-. S, C. SARKAR ON THE BUCCAL GLANDS 



In his plate Tomes has given figures of sections of four or 

 five teeth, and he has shown the bending in one only, and this 

 also at the anterior side. This evidently proves that this was 

 one of those hinged teeth. 



This knob-like structure at the anterior edge of the tooth fits 

 into the slightly concave, vertically inclined, smooth facet of the 

 bone, so that yvheu the tooth is pressed forward it strikes against 

 the slightly inclined plane and is prevented from further 

 bending. At the posterior side the distance between the bone 

 and the end of the tooth is greater. The connective tissue 

 between these two structures is more prominent, and its 

 histological structure can be examined. Under the high power it 

 has the appearance as shown in text-figs. 3 and 4, and it resembles 

 white fibrous tissue. It has not at all the appearance of develop- 

 ing bone or enamel. Had it been enamel it would have been 

 dissolved by the continued action of the acid in the decalcifying 



Text-fiffure 3. 



Tropidonofus stolatus. Longitudinal section of maxilla, showing a loose tooth 

 with its connective-tissue attachment. I. ligament; ma.r. maxilla; p.c. 

 pulp cavity. X 260. 



solution, to which it was subjected for more than a month. 

 Text-fig. 4 shows also the connection of the saiiie tooth at the 

 posterior edge. It will be noticed that the connective tissue {I) 

 keeps it attached to the bone. Thus we see that the tooth Avhen 

 pressed from in front moves so that the hinder end of the 

 base, which has a greater field in which to move, is pressed down 

 on to the bone ; but it is prevented from slipping further b_v 

 the connective tissue ; while, on the other hand, if the tooth 

 is pressed forwards from behind, its power of movement is 

 restricted by the inclined edge of the socket of the bone and 

 also by the band of connective tissue at the hinder end, which, 

 so far as can be ascertained at present, appears to be non- 

 elastic. This hinged and fixed arrangement I have found to be 

 extended to the grooved teeth. If there are two grooved teeth, 

 one of them is hinged and the other fixed. It depends upon the 

 arransement of the other teeth whether the anterior or the 



