288 



PHYSIOLOGY 



CHAP. 



In every case in boys a rapid increase in stature is associated 

 with a slow increase in weight and bulk. Children, especially those 

 who are plump and blooming during their first years, gain rapidly 

 in height at the end of their third or fourth year, but they 

 become at the same time thinner and less robust ; this is the 

 period of the first increase in height. Between the eighth and 

 tenth year there is generally observed a new period, known as 

 the second increase in height. 



In order to form an idea of the way in which the proportions 

 of the body vary during growth, we may take as a working basis 

 the relation which is almost constant between the length of the 

 head and that of the body. The total length of the child at birth 

 is four times that of the head ; at two years of age it is five, at 

 six, six ; at fifteen, seven ; and in the adult eight times as long. 

 This is shown by the following table, which may be regarded as 

 the standard of average measurements : 



At the beginning of puberty the increase in height is very 

 small ; on the other hand, the increase in weight is very great 

 (Pagliani), being in the next two or three years about twice as 

 great as before; for this reason some physiologists apply the 

 term turgor tertius to this period. Later on the increase in weight 

 becomes normal again, and from the fifteenth year in girls and 

 the seventeenth in boys, when the weight at this age reaches 

 50 kg., the increase becomes gradually less until maturity is 



