1012 



THE PHYSIOLOGY OF REPRODUCTION. 



countiy especially by Bowditch, Porter, Beyer, and Holt.* An 

 interesting feature of the records collected by Bowditch (Fig. 308) 

 is the proof that the prepubertal acceleration of growth comes 

 earlier in girls than in boys, so that between the ages of twelve and 

 fifteen the average girl is heavier and taller than the boy. Later, 

 the boy's growth is accelerated and his stature and weight increase 

 beyond that of the girl. Robertson f has accumulated some facts 

 which indicate that the growth of the individual does not proceed 

 with a uniformly accelerated or a uniformly retarded velocity, but 

 rather in cycles. Most of the curves of growth, such as is rep- 



Fig. 308. — <jraphic representation of Boston school children based on Bowditch's figures, 

 giving the relations of weight to age and of height to age. (Bigelow, "Wood's Reference Hand- 

 book of Medicine.") 



resented in Fig. 308, give the relation between age and weight or 

 age and stature. These relationships are subject to racial varia- 

 tions, and for the purpose of determining whether or not growth is 

 proceeding normally it has been suggested that the ratio of weight 



to height, i^^i^, furnishes a more practical index, and one that 

 is not disturbed by racial characteristics, f Observations have 

 established the relationship indicated in the table on p. 1013, which 

 gives the weight corresponding to any given height at each age. 

 Variations from this ratio greater than 10 per cent, are taken to 



* See Bowditch, "Report of State Board of Health of Massachusetts," 

 1877, 1879, and 1891; Porter, "Transactions, Academy of Science," St. Louis, 

 1893-94; Beyer, "Proceedings of United States Naval Institute," 21, 297, 

 1895. 



t Robertson, "American Journal of Physiology," 37, 1, 1915. 



j Holt, "American Journal of Diseases of Children," 16, 359, 1918. 



