IV PREFACE. 



kindness of Mr. Carle 0. Warren, of the Marquand School, Brooklyn, 

 the photographs of boys of various ages shown on plates 4 to 6 were 

 secured. Dr. Harvey G. Beck and Dr. L. F. Barker gave permission 

 for the republication from Barker's "Endocrinology and Metabolism" 

 of the photographs at the bottom of plate 8. The families who have, 

 on request, furnished special data are too numerous to mention. To 

 all of the foregoing I desire to express sincerest thanks. 



I 



