10 



THE OX AND THE DAIRY. 



on each side of this central pair cuts the gum, making the 

 number four ; at the end of the third week, the number will 



THIRD WEEK. 



be increased to six ; and at the termination of the fourth 

 week the full number of the deciduous, or milk-incisors, will 

 be complete. At this time the upper line of the sharp edges 

 of the two central incisors has begun to wear, the osseous 

 portion of the tooth appearing where the enamel is abraded ; 

 this increases, and, in the course of two months, the next teeth 

 will begin to show signs of wearing, and in about three 

 months the next in succession ; till in the course of four 



FOURTH WEEK. 



months or a little more, the whole set show the effects of use, 

 but the four central teeth by far the most decidedly. At this 

 time, independently of their wearing down by attrition, the 

 two central teeth begin to diminish in size ; at first this is 

 not very perceptible, but in the course of a few months, the 

 change will be very palpable. This diminution is the result 

 of a process of absorption, which goes on with increased 

 rapidity as the new teeth, in their nutrient cells beneath, 

 become more and more developed ; the worn surface of the 



