294 



COMPARATIVE PHYSIOLOGF. 



New-bom. 



8 days. 



4 weeks. 



1 year. 



2 years. 



2} years. 



3 years. 



3} years. 



'4 years. 5 years. 



FiQ. 245 (1).— Changes in incisor teeth of ox with age (Wilckens). 



