THE TEETH. 539 



predating special ideas. Buffon has very truly said that the earliest 

 period of conscious existence is a scene of pain, the life of the infant "be- 

 ing divided between sleep and crying ; from its slumbers it is awakened 

 only by the pains of hunger ; nor is it until after the lapse of many days, 

 or even weeks, that the first smile is seen. It is too feeble to turn from 

 side to side, but remains in the position in which it was placed. Its 

 skin, which at birth was covered over with a whitish incrustation, the 

 vernix caseosa, becomes reddish, the depth of this tint, however, shortly 

 passing away. At this period, moreover, life is purely vegetative, the in- 

 fant feeding and sleeping. The biliary matter, meconium, which had ac- 

 cumulated in its intestine during foetal life, is discharged in the course of 

 a day or so after birth, and the digestive apparatus enters on its functions 

 with activity. 



It is said that the infant smiles soon after it is forty days old ; though 

 it can cry it can not shed tears. Before long it gives indications of its 

 satisfactions and dislikes. The power of moving in an erect posture is 

 gained by it in the course of a year, and by the close of that time it can 

 masticate. Of its teeth, the central incisors appear about the 

 seventh month, those of the lower jaw first ; the lateral incisors 

 about the eight or tenth, the anterior molars about the twelfth, and the ca- 

 nines about the eighteenth, the posterior molars being cut between that 

 time and three years. The average date of the appearance of the perma- 

 nent teeth is, the front molars about the seventh year ; middle incisors, 

 eighth ; lateral incisors, ninth ; anterior bicuspids, tenth ; second bicuspids, 

 eleventh ; canines, twelfth to thirteenth ; second molars, twelfth to four- 

 teenth; and the last molars from the seventeenth to the twenty-firs, t year. 



The power of articulate speech is displayed within twelve or fifteen 

 months, some letters being more easily gained than others ; among 

 themareA,B,P,M. 



From henceforth the mind emerges with rapidity from the confusion 

 of a multitude of impressions, and learns to concentrate itself Concentration 

 at pleasure upon one. This capability of mental abstraction of the atten- 

 is a process of specialization, and is a manifestation of the tlon ' 

 law of Von Bar. The intellectual difference which we eventually observe 

 between one man and another is, to no inconsiderable degree, dependent 

 upon such an ability of concentrating thought. He who conceives of a 

 thing distinctly is very likely to express -himself of it clearly. 



Throughout infancy and childhood, the features, and even the gestures, 

 indicate the profound constitutional changes which are going on. The 

 countenance, instead of expressing pleasure and pain in the aggregate by 

 smiling or crying, as was the case at first, gains the faculty of represent- 

 ing every grade of feeling. Long before maturity is reached we read 

 without difficulty the thoughts which are passing in the mind from the 



