vii THE STAGES OF LIFE AND DEATH 283 



its height is more than double that at birth. During the following 

 years there is a growth of 50 to 75 cms., the full height being 

 attained between 20 and 25 years of age. Growth is not uniform 

 and continuous, but is slower at times, and even checked altogether 

 for a time, only to begin again suddenly. 



MacDonald prefers to estimate individual growth by the 

 criterion of weight, though many causes, such as obesity and 

 disease, tend to make this unreliable. 



The increase in weight equally with that of stature is subject 

 to fluctuations, but they do not however correspond to one another. 

 During the first months the infant increases very rapidly in 

 weight, but this rate is not maintained. At the end of the first 

 month the weight is almost twice, at the end of the first year it is 

 more than three times as much as that at birth. 



Th. Rotch (Boston) distinguishes in children the chronological 

 from the anatomical age, inferred from the phases of the develop- 

 ment of the bones, which he regards as connected with the 

 physiological conditions of the organism as a whole. From radio- 

 graphs taken of different parts of the body of over 500 children 

 in conditions apparently normal, Eotch came to the conclusion 

 that the successive appearance or development of the carpal bones 

 may be taken as an index of anatomical groioth in order to 

 determine the different periods of childhood. 



IV. Childhood lasts from birth to puberty. As a rule, 

 authorities on the subject (Martian, Vierordt, and others) recognise, 

 apart from slight divergences, three periods. 



() Early childhood or infancy comprises the first two years of 

 life, with the exception of the brief phase of the new-born child 

 which we have already studied. During the first year the child 

 has no teeth and lives entirely on milk, it neither speaks nor 

 walks, its psychic acts are rudimentary, involuntary reflex actions 

 predominating, and it falls asleep readily after it has been fed at 

 the breast. In the second year the purely milk diet ceases, and 

 the child begins to stand, and little by little to walk ; with the 

 development of the visual and auditory sensations begin the first 

 signs of psychic life and the manifestation of that life in the 

 gradual development of articulate language. The salient charac- 

 teristic of this period is rapidity of development (which as we 

 have already seen is greater than during any other period of life) 

 and the appearance of the first dentition. The lower central incisors 

 are the first to be cut at about seven months ; at about two and 

 a half years of age the four last premolars appear, and the child 

 now possesses twenty teeth, which form the temporary or milk 

 teeth. 



(/>) The second or middle period of childhood lasts from the 

 second to the fifth or sixth year, that is until the^rs^ four large 

 permanent molars are cut, with which the second dentition begins 



