1923. No. 4. PHYSICAL DEVELOPMENT OF CHILDREN AND YOUNG PEOPLE. 53 



As to the girls, the index curves show decline until 12, then incline. 

 Now, one should naturally not permit oneself to be influenced suggestivelv 

 by the index curves and insist upon seeing a precise division at 12. 

 The numeric differences around these years are, in the first place, too 

 small, and. in the second, there must with photographs be room for a 

 small margin (cf. page 49). From the photographs we see more of a 

 plumpness in the 14 years old girl than in boys of the same age. The 

 sight-impression of the complete series 7 — 14 does not deny the numeric 

 result of the mass-material. We can safely enough take it for granted, 

 that the Bartels-Stratz schedules are subjective structures, not objektive 

 natural science. 



Series-photographing is furthermore of importance for the question 

 of the periods of the average puberty development. First the boys: 

 Averagely^^ the year classes are entirely "infantile" to and including i^. 

 At 14 we perceive until the great )najoriiy the first proper signs of 

 puberty, a distinct enlargement of the testes. Of 14 photographed middle 

 types of this age (only 2 are reproduced here. cf. page 49) enlargement 

 of testes was found distinctly in 9, while in 18 photographed 13 year 

 olds the same phenomenon is found in 8 or 9 (2 are reproduced here). 

 It is now of considerable interest, of course, that the strong development 

 in height and absolute weight sets in just at this period, after year 13, 

 or in the 14th year. 



A parallel phenomenon for the girls — an enlargement of the ovaries 

 — cannot be proved in vivo. But when we investigate the year class 

 where the girls shoot out both in height and weight, after 11, or in the 

 I2th year, we can also for this sex prove, that just this period exhibits 

 the first visible signs of puberty, or the beginning special development 

 of the breast glands. In the great majority^- of the 12 years old girls 

 "areolamamma" could be proved — papilla and areola together forming 

 a small eminence. The great majority of the 11 years old girls fi/) 

 are absolutely "infantile". 



It is evident that the statistical value of a number as above 

 mentioned would be very insignificant, it the children had been taken 

 out indiscriminately. The value, however, increases very strongly bv 

 the exceedingly small numeric deviations from the middle norms. 



From this simultaneousness between the first appearance of the 

 visible signs of development into an individual able to propagate and 

 the beginning vigorous growth in weight, it may be concluded, that it 

 is right to reckon the "pre-puberty" period from and including the time, 

 when this vigorous growth sets in. 



^' .III the photographed children are here included. 



" To mention the number concisely cannot be done, -is not all the photographs permit 

 a sufficiently definite determination of this commencing transition. 



