CHAPTER VIII. 



linear series — continued, mammae. 



Some of the phenomena of Meristic Variation are well seen in 

 the case of mammae 1 , and especially in the modes by which increase 

 in the number of these organs takes place. 



The facts regarding these variations in Man have so often been 

 collected that it is scarcely necessary to detail them again. For 

 our present purposes it will be sufficient to give a recapitulation 

 of the chief observations in so far as they illustrate the pheno- 

 mena of Variation. 



The most important collections of the evidence on this subject 

 are those of Puech 2 , Leichtenstern 3 , and Williams 4 , from whose 

 papers references to all cases recorded up to 1890 maybe obtained. 

 Besides these, Bruce 5 has given a valuable account of a consider- 

 able number of new cases together with measurements and statis- 

 tical particulars. These accounts contain almost all that is known 

 on the subject but additional reference will be made to original 

 authorities in a few special cases. 



In Man supernumerary mammae or nipples nearly always occur 

 on the front of the trunk, being usually placed at points on two 

 imaginary lines drawn from the normal nipples, converging in the 

 direction of the pubes. These lines may thus be spoken of as the 

 " Ma miliary lines." It is with reference to supernumerary mammae 

 occurring on these lines that the subject of mammary variations is 

 chiefiy important to the study of Meristic Variation. In addition 

 to these, however, there are a few well authenticated examples of 

 mammae placed in parts of the body other than the mammary lines 

 and of these some mention must be made hereafter. 



1 It will be understood that facts as to variations consisting in absence of 

 mammas or nipples and other such changes do not come within the scope of this 

 volume, but belong rather to the province of Substantive Variation. 



2 Puech, Les llamelles et leurs anomalies, Paris, 1870. 



3 Leichtenstern, Virch. Arch. f. path. Anat. u. Phys., 1878, lxxiii. p. 222. This 

 collection was apparently made independently from that of Puech. 



* Williams, W. Rooer, Jour. Anat. Phys., 1891, xxv. p. 225. 

 5 Bruce, J. Mitchell, Jour. Anat. Phys., 1879, xm. p. 425. 



