22 ON ABSORPTION. 



only is pressure in itself inefficient for the purpose, 

 but that mammals were liable to abnormal con- 

 ditions in the development of those organs before 

 the period of the human epoch. 



Since the hypothesis of pressure of the new tooth 

 against the old, which could not have stood the 

 test of a single dissection, has been given up, there 

 has been a tendency among modern observers to 

 run into the opposite extreme, and to account for 

 the process as one totally independent of the new 

 organ. 



This notion was first asserted by Hunter,* who 

 affirmed, that " when the first set falls out, the suc- 

 ceeding teeth are so far from being destroyed, by 

 their pressure, the parts against which they might 

 be supposed to push, that they are still enclosed 

 and covered by a complete bony socket." 



It was repeated by Bell,t who. calls it a process of 

 anticipation, but qualifies the general acceptance of 

 the hypothesis, by asserting that "the presence, 

 though not the pressure, or even contact of the 

 new body, is necessary to excite the action of the 

 absorbent vessels." 



And, very recently, Mr. Tomes has not only 

 accepted the same opinion, but carries it still 

 further. If I gather correctly from the general 

 tenor of his paper, | he asserts that a papilla is deve- 



* " Microscopic Journal," vol. iv. 



f " Natural History of the Human Teeth." (Palmer's Edition.) 



+ " On the Teeth." 



