98 



I. Their distribution occurs in an area where supernumeraries 

 have been observed in adults, i. e. in the breast region chiefly, under 

 the arras and, in a few cases, in the inguinal region. 



II. In form and histological detail they closely resemble the earlier 

 stages of the true mammary Anlagen. 



III. The time of their appearance corresponds with that of the 

 early stages of the true mammary Anlagen and before that of any 

 other known epithelial structures. 



IV. There is no other plausible explanation. The epithelial struc- 

 tures of this region, namely, Montgomery- glands, sweat glands, seba- 

 ceous glands and hair-Anlagen, are known to arise considerably later. 

 Moreover, if these epithelial thickenings were destined to give rise to 

 any of the structures just mentioned they ought to be found still per- 

 sisting in embryos slightly older, but an examination of embryos of 

 64, 65, 150 and 229 mm in length showed that they had entirely van- 

 ished. Schmidt therefore comes to the following conclusion: There 

 occur in man normally, hyperthelial Anlagen which are 

 usually temporary since in the newly-born and in adults 

 only one pair of mammae are ordinarily present. The 

 occasional persistence, however, of these temporary epithelial thickenings 

 would explain the presence in man of supernumerary mammary organs. 



In 1898 Heinrich Schmitt (17) examined a series of seventeen 

 human embryos ranging in size from 9,5 to 115 mm, in seven of which, 

 namely those between 17 and 45 mm in length, the same sort of 

 epithelial thickenings were found. He does not however agree with 

 Schmidt that they are all to be explained as Anlagen of supernumer- 

 ary mammae but he is unable to give any interpretatioD of their 

 significance other than that they certainly have some connection with 

 the mammary apparatus. 



In 1898 Strahl (19) makes incidental mention of finding epidermal 

 thickenings, which are doubtless the Hugo Schmidt - structures, in a 

 24 mm human embryo but he does not go into details regarding their 

 size, form, locality and numbers, nor does he discuss their significance. 

 Aside from the three authors mentioned above nothing, so far as I 

 am aware, has been written with regard to these particular structures 

 in man. 



Since 0. Schultze's (18) discovery of the mammary line on the 

 pig in 1892 several papers have appeared concerning the earlier phases 

 of the development of the mammary organs in other mammals than man 

 and those referring also to supernumerary Anlagen have an interest in 

 this connection. Supernumeraries have been recorded for the cow by 



