Ill] OF PRE-NATAL AND POST-NATAL GROWTH 75 



According to His*, the following are the mean lengths of the 

 unborn human embryo, from month to month. 



Months 01 2345 6 7 89 10 



(Birth) 

 Length in mm. 7-5 40 84 162 275 352 402 443 472 490) 



500) 



Increment per — 75 325 44 78 113 77 .50 41 29 18 1 



month in mm. 28 I 



These data link on very well to those of Riissow, which we 

 have just considered, and (though His's measurements for the 



2 4 6 



Fig. 8. Mean monthly increments of length or stature of child (in cms.) 



8 10 12 14 16 18 20 22 



months 



pre-natal months are more detailed than are those of Riissow for 

 the first year of post-natal life) we may draw a continuous curve of 

 growth (Fig. 7) and curve of acceleration of growth (Fig. 8) for the 

 combined periods. It will at once be seen that there is a "point 

 of inflection" somewhere about the fifth month of intra-uterine 

 life f : up to that date growth proceeds with a continually increasing 



* Unsere KorjKrforrn, Leipzig, 1874. 



t No such pomt of inflection appears in the curve of weight according to 

 C. M. Jackson's data (On the Prenatal Growth of the Human Body, etc., Arner. 

 Journ. of Anat. ix. 1909, jip. 126 156), nor in those quoted by him from Ahlfeld, 



