SEXUAL 1)111 Kl IN i:i ll.D. 7 



Proceeding by a method to be developed later, I have divided adult 

 build into five classes, and counted for the various matings the Dumber 

 of children falling into each. (See tables 1 and 2. ) The a index 



of build, obtained from the individual indices of build, is 2.52 I metric 

 system) or 35.81 ± 0.12 (English system) for males, and 2.43 

 (34.54 ± 0.13) for females, a difference of only 3.7 per cenl in favor 

 of the males, a difference that for our purposes can be neglected. A 

 separation of the sexes in our studies will therefore be, ordinarily, 

 not attempted, and this has the advantage in giving us larger fre- 

 quencies in our tables. 



Racial Differences in Build. 



That there are marked racial differences in build is notorious. The 

 slender Scotchman (plate 1, fig. 3) is in striking contrast with the 

 South Italian, Greek, or Russian Jew (plate 2, fig. 3). The Eskimo 

 are noted for their fleshiness, but Arctic conditions seem to favor la 

 build. (See Davenport and Love, 1921, p. 165.) Martin (1914, p. 

 248) gives an average body-build of 1.42 (2.3 our system) for South 

 Russian Jews and 1.07 (1.7 our system) for Bushmen. Probably the 

 Nilotic negroes are the slenderest race on earth (Martin, 191, p. 21 

 for photograph see Martin, p. 203, or Davenport, 1917, p. 347). The 

 racial differences in body-build are so great that, when feasible, race 

 should be taken into account in studies on body-build. 



Geographical Differences in Build. 

 Apart from race, it seems probable that climate influences build. 

 The races that live in the north polar region are of stout build, but 

 this may be a racial trait. On the other hand, the whites who come to 

 live near the pole are heavier than those who live near the equator. 

 This may be due to relative freedom in the subpolar area from certain 

 diseases which reduce weight. There may. however, be a physiolog- 

 ical response of the body to the long, cold winters. Whatever 

 explanation, men from Alaska were found, at mobilization of the 

 United States Army in 1917-1S, to have a much higher index of build 

 than those from any other region, i.e., 2.28 (32.41 >: North Dakota 

 and South Dakota came next, with indices of 2.24 (31.85) and 2 

 (31.73) respectively. These were followed by Montana. Mini 

 and Wisconsin. Contrariwise, the recruits from the Gulf States had 

 a low index of build. Whatever the determining causes, geographical 

 differences in build do exist. Consequently, in studies of build, r 

 desirable to consider the residences of the persons studied. 



"The method of measuring build i- -I The smaller 



between 1.5 and 4.5) is the metric index The lirir-r in lei [2 » up U> 100 

 system index, and is usually 8 1 without decim 



