100 



In addition to the normal milk points ("Milchhiigel", Bonnet), 

 five isolated thickenings of the epidermis are found on each side si- 

 tuated so far within the axillary region as to be entirely hidden from 

 view on the model until the arms were cut oft' at the shoulders. The 

 relative position of these structures is shown in Diagram I. There is 

 no area of thickened epithelium present which could be termed homo- 

 logous to the "Milchstreifen" (Scbtvvalbe) found in younger embryos. 

 See Table I. Moreover the fact that these epithelial thickenings are 

 isolated and without bridges of raised epithelium connecting them shows 

 that, whatever they may have been formerly, they are not at present 

 to be regarded as a mammary line ("Milchlinie", Schultze) such as 

 has been described by various authors for earlier stages. See Table I. 



A tabular description of the size, shape and locahty of each epi- 

 thelial thickening, including the true milk-points, is given in Table II. 



In addition to these pectoral Anlagen a small, somewhat spherical 

 outgrowth of epithelium about 90 i-i in diameter was found in the in- 

 guinal region near the attachment of the leg to the body on either 

 side. Its form on the left side is shown in Fig. 4 and the corre- 

 sponding growth on the right side is quite similar. 



This is the youngest human embryo in which the Hugo Schmidt- 

 structures have been described as a glance at Table I will show. 



Piper I S, Preserved in chrom - aceto - sublimate , stained with 

 borax-carmine, embedded in paraffine and cut into 1284 cross-sections 

 of 15 f,i each. Length about 22,4 mm from forebrain to coccyx and 

 about 22 mm from hindbrain to coccyx. In age it stands between 

 Fig. 24 and Fig. 25 of His' table and is consequently about 56 days 

 old. The epithelium was excellently preserved throughout. Two wax 

 reconstructions were made, one enlarging the entire embryo 13 ^/g 

 times (every fifth section being used), the other, enlarging 33^3 times 

 that area alone including the epithelial thickenings (every other section 

 being used). 



In this embryo there are forty epithelial thickenings of the sort 

 described by Hugo Schmidt besides the two milk points but nothing 

 which could be called either a mammary line or a "Milchstreifen" is 

 present. In addition a pair of spherical epidermal structures, homo- 

 logous to those seen in the inguinal region of Piper II, appear in this 

 embryo also (Fig. 14) but, since they evidently belong to a difl'erent 

 category than the forty pectoral Anlagen, they are not included in the 

 descriptive tables. Schmitt found these inguinal proliferations in one 

 of his embryos (Table I, 24) as is shown by the following: "Außerdem 

 findet sich beiderseits je eine eigentümliche, nach der Achsenhöhle zu 



