THE VISCERA. 203 



It happens in the following order. At the seventh month the central in- 

 ferior, after them the remaining (generally, the central superior, first) incisor 

 teeth ; at the end of the first year the first molars ; in the middle of the second 

 year the inferior canine, later the superior, and, at the end of the second year, 

 the second molars ; in the whole twenty teeth. 



[Formula: incisors -; canine - -; molars - - = 20. TRANS.] 

 4 1 1 & & 



These milk temporary teeth, d. lactantes s. temporarily remain until the or 

 seventh year, when they make room for the permanent, d. permanentes. The 

 milk teeth are smaller and narrower, the crown and root do not pass gradually 

 into one another, but are separated by a kind of circle ; the (superior) first 

 temporary molar has three roots (the permanent only one) ; the (inferior) 

 first temporary molar, a crown with several and sharp points, and a double 

 root; the second temporary molar a broad crown and five points, with a 

 double or three-fold root. 



c. The change of teeth, mittatio dentium, dentitio secunda. The (thirty-two) 

 permanent teeth are also developed from dental sacculi, of which those which 

 ought to occupy the places of the twenty temporary teeth are situated in the 

 same cell with them, the twelve to be newly added in their own proper cells. 

 The germs form in the following order: in the fifth month of embryonic 

 life the germ of the third molar tooth arises, in the eighth month that for the 

 remaining incisor teeth, at the end of the first year that for the canine, and 

 rather later that for the fourth molar ; in the eighth month after birth the 

 germ for the first and second; in the fourth year that for the last molar. 



The decadence of the temporary teeth is preceded by a diminution of the 

 artery which passes to each, whereby the root of the tooth is first absorbed, 

 and the bony canal of the artery contracted ; then, in the ninth year, quite 

 closed. 



The eruption of the permanent teeth takes place in the following order : 



( The middle pair of the superior, later, that of 

 In the seventh year appear 2 the inferior Incisors. 

 The three Molar teeth. 



In the eighth year - 



****** 



In the ninth year The first and second Molars (below and above). 



In the twelfth to the thir- ) rr,, n 

 teenthyear | The Canine. 



In the fourteenth or later The fourth Molar, and 



Between the twentieth and ) rp, 



I . . ^ > The last or wisdom teeth. 



d. The decadence of the teeth in old age is normal, and appears to be 

 effected by the pulp of the tooth, by degrees, ossifying, and the nourishing 

 vessels becoming obstructed. The cells also in which the teeth are seated 

 fill with bone earth (the teeth become apparently longer), their edges become 

 absorbed, and, in consequence, the jaws lower, the gum, after the decadence 

 of the teeth, draws over the free surface, and becomes cartilaginous (as it was 

 before in the suckling). The decay of the teeth appears also to be in con- 

 nection with the grinding away and loosening of the enamel ; the crown is 

 alrr-acly \vorn even before the teeth are completely perfect. 



Anomalies in the number of the teeth. Most frequently the wisdom, 



