102 



II. The arraDgement of the Anlagen with reference to one another 

 makes their derivation from a longitudinal mammary line, such as is 

 now known to be the stage of development preceding the milk points, 

 doubtful. Even in the case of Piper II (see Diagram I) where the 

 Anlagen at first sight appear to be somewhat linear in arrangement, 

 the direction of these lines cephalo-caudally is divergent instead of 

 being convergent as is the rule in human supernumeraries when present. 



III. Moreover reference to Tables II, III and IV shows that the 

 majority of these Anlagen are wider than they are long. This 

 is also true of the cases recorded by Schmidt and Schmitt. If 

 these Anlagen are the relics of what was once a longitudinal ridge 

 (mammary line) the reverse would naturally be expected. Therefore 

 the arrangement of the Anlagen with reference to their long axes makes 

 it improbable that they are fragments of a longitudinal line. 



IV. Hugo Schmidt however does not attempt to derive these 

 structures from the mammary line but from a much larger and more 

 diffuse area of raised epithelium — the so-called "Milchstreifen" — 

 which he finds present in certain instances. Reference to Table I 

 will show that such an area of thickened epithelium has been very 

 generally found in younger embryos. Strahl and Hirschland hold 

 this area to be phylogenetically important as the stage of development 

 preceding the mammary line and so find in their 4 mm embryo 

 (Table I, 1) the very first Anlagen of the mammary apparatus in man. 

 If this is the true view the erratic distribution of the Hugo Schmidt- 

 structures is easily accounted for by saying that they have their origin 

 in this broad area of raised epithelium, and are therefore homologous 

 to the true milk points. Doubt is cast on the phylogenetic importance 

 of the "Milchstreifen", however, by the fact that a similar arrangement 

 of cells occurs, as pointed out by Heinrich Schmitt, in selachians, 

 reptiles and birds where mammary Anlagen are out of the question. 

 Again the fact that the "Milchstreifen" in man extends not only down 

 the sides of the body between the appendages but also over the gill- 

 arches and over the stumps of the appendages as well as out on to 

 the tail, w^ould seem to indicate that it is to be interpreted as an 

 ontogenetic phenomenon connected with the mechanics of growth and 

 of little phylogenetic importance so far as the mammary apparatus is 

 concerned. In fact Profe (12) and Beard (2) advance this explanation 

 for even the mammary line itself. The conclusion is that, even if it 

 were proven that the Hugo ScHMiDT-Anlagen arose from this thickened 

 area ("Milchstreifen") it would by no means follow that they were of 

 equal phylogenetic worth with the milk-points and could in consequence 



