Physiological Age. 



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15 (270 

 Physiological Age. 



By 0. WARD CRAMPTON. 



[From the Department of Physical Training, Board of Education, 



New York City.'] 



The term physiological age refers to the stage of development 

 in contradistinction to age in years and months, which is the usual 

 method of designating age. Various evidences of physiological 

 age are tooth appearance, pubescence, change of voice, menstru- 

 ation, menopause, etc. 



Pubescence is an evidence of sexual ripening and the beginning 

 of adolescence. For the purpose of record, three physiological 

 groups are distinguished corresponding to three successive stages 

 of development (1) prepubescence, (2) pubescence, (3) post- 

 pubescence. The first group is characterized by an absence of 

 hair upon the pubis, the second is an intermediate stage, the third 

 group have hair upon the pubis. The data of the results below 

 are taken from 4,500 New York High School boys, and are 

 divided into half year age groups designated by the middle age 

 value. The following table shows the percentage composition of 

 each chronological age : 



Age. 12.75 13-75 13-75 H-25 14-75 >5-25 »5-75 16.25 16.75 J7-25 J7-75 



Prepubescent 69% 55 41 26 16 9 5 2 I o o 

 Pubescent 25% 26 28 28 24 20 10 4 4 2 o 



Postpubescent 6% 18 31 46 60 70 85 93 95 98 100 



It gives also the relative size of the subgroups. These facts 

 have been hitherto disregarded and the chronological age group 

 treated as if it were homogeneous. 



These subgroups in each age exhibit characteristic differences 

 in physical measurements which differences are far greater than 

 the difference between contiguous year groups. 



At the age of 15.75 the postpubescent group (85 per cent, of 

 all) are 34 per cent, heavier, 32 per cent, stronger and 9 per cent, 

 taller than the prepubescent group (forming 5 per cent, of all at 

 the same age) as indicated on the next page : 



