22 THE STRUCTURE OF MAN 



proportion of 1 in 19. In every nineteenth man, then, we find 

 the atavistic reappearance of supernumerary mammse. 

 The following is an analysis of these cases : 



On the right. On the left. 



One teat . . . . 24 cases. 36 cases. 



Two teats . ... 3 3 



Other combinations . . . 2 ,, 2 ,, 



One trace .... 8 35 



Two traces ....'. 3 7 



Other combinations . . . 2 ,, 2 



The preponderance of teats on the left side is as 1'4 to 1, 

 and in the case of traces of these organs it is still more striking, 

 viz. as 3 '3 8 to 1. This is no doubt to be associated with 

 the well-known fact that the normal left breast in women is 

 often (always?) more developed than the right (cf. ante, p. 19), 

 and it may be that the right, therefore, degenerates more rapidly 

 than the left. 



In those cases recorded in the literature of the subject in 

 which one of the normal teats is entirely absent (amasty), the 

 right nipple is more frequently wanting than the left. 



In the cases recorded by Ammon (if we reckon together the 

 number of teats and teat traces occurring singly) the proportion 

 of those on the left to those on the right is 71 to 32. These 

 results agree pretty closely with those of Leichtenstern. 



In one of the cases with a pair of supernumerary teats, 

 Ammon found these considerably to the side, quite near the 

 anterior axillary fold formed by the edge of the pectoral muscle ; 

 and in a case described by Leichtenstern they had even entered 

 the axillary area. 



This shifting apart is explained by Ammon as connected 

 with the upright gait of Man, i.e. with the position of the upper 

 extremities, which is secondarily acquired as a result of it. 



The following case, observed by Ammon, is particularly 

 interesting, as a striking example of the extraordinary persistence 

 of certain organs which, after becoming as a rule extinct, 

 occasionally reappear. 



On the upper part of the breast of a very hairy soldier, two 

 diverging hair vortices occurred a few centimetres above the teats, 

 but farther apart than these, and nearer the axillary folds (* Fig. 

 15). At the focal point of each of these vortices there was a 

 light spot from which the hair grew upwards and outwards as 



