ATAVISM. 175 



By far the most remarkable situation in which milk- 

 glands arise, is in the interior of some peculiar skin-con- 

 taining tumours of the ovary. I have traced every stage 

 from a sebaceous gland to a nippled mamma, furnishing 

 milk, in such tumours a situation in which it would 

 puzzle even Paley to imagine a useful purpose. 



These facts indicate clearly enough that a mamma 

 may make its appearance in any situation of the body 

 if the favouring conditions exist i.e., a cutaneous 

 recess abundantly supplied with sebaceous glands, and 

 preferably on the ventral or protected aspect of the 

 body ; warmth and moisture appearing to favour their 

 development. 



The careful consideration of such cases clearly shows 

 that to attribute such aberrant mammae to atavism 

 is inconsistent with sound reasoning : it is, however, 

 obviously erroneous to regard all forms of supernumerary 

 mammae and nipples as "sports," but I am firmly of 

 opinion that only those occurring in the line of the 

 deep epigastric arteries, excepting those clearly due to 

 dichotomy, can be with any justness considered as re- 

 versionary. In the section on tumours we shall have to 

 return to this subject, especially in reference to cancer. 



