103 



be termed Anlageu of supernumerary mammae. Therefore, the deri- 

 vation of the Anlagen from the "Milchstreifen" does not necessarily 

 make them homologous to the true milk glands as the supernumeraries 

 would need to be. 



V. Bardeleben (1) summarizes data from various sources and 

 shows that out of 2894 cases of supernumeraries in adult man 2224, 

 or 777o, are located below the true mammary glands. Lichten- 

 STERN, as cited by Hugo Schmidt, out of 105 observations finds 91 ^/^ 

 below. Table V shows the locality of the 266 Hugo Schmidt- An- 

 lagen which have been described. The result is not what would be 

 expected if these are the Anlagen of supernumeraries, for only 29°/j, 

 occur below the milk points. 



In passing it may be observed that Bardeleben finds decidedly 

 more supernumeraries on the left side than on the right i), while re- 

 ference to Table V shows that the difference in the observed cases of 

 the Anlagen in question is too slight to have any significance. Thus 

 the locality of these Anlagen does not entirely correspond with that 

 of the true supernumeraries. 



In the absence of any hypothesis that would explain the facts 

 better Hugo Schmidt's explanation has been accepted. A recent paper 

 by Bresslau (4) on the development of the mammary apparatus in 

 marsupials may, however, afford the clew needed. 



He found in the opossum (Didelphys marsupialis) that the 

 development of the marsupial pouch is preceded by the formation of 

 marsupial pockets ("Marsupialtaschen") around each milk point. 

 Their arrangement around the several milk points was made entirely 

 plain by wax reconstructions. These "pockets" appear at first simply 

 as an irregular ring of thickened epithelium which sinks into the cutis 

 underneath. It is certain these marsupial pockets are not homologous 

 to the marsupium itself since this organ develops later, its Anlage 

 being farmed by the uniting of the outer edges of the chain of mar- 

 supial pockets themselves while the remainder of these temporary 

 structures surrounding the milk points entirely disappears. May not 

 the hyperthelial structures of Hugo Schmidt be homolo- 

 gous to the marsupial pockets of Bresslau? 



Some of the reasons which point to the probability of this hypo- 

 thesis are as follows: 



1) Right Left Both Total 



Instances 3079 3459 1490 8028 

 • Percent 38 43 19 100 



