RECORDS OF MEETINGS 303 



SECTIOK OP BIOLOGY 



11 Decembee, 1916 



Section met at 8 :15 p. m.^ Vice-President H. von W. Schulte pre- 

 siding. 



The following program was presented : 



H. D. Senior, The Development of the External Iliac Artery 



IN Man. 



Halsey J. Bagg, The Genetics of Certain Types of Animal Be- 

 havior. 



John T. Nichols, Development and Distribution of Presh-water 

 Pishes in Africa. 



Summary of Papers 



Professor Senior stated that in man and pig the femoral artery is not 

 developed directly from the hypogastric, as described by Hochstetter in 

 cat and rabbit/ but that the femoral and inferior epigastric arise from 

 a common stem (the external iliac), which antedates them both consid- 

 erably in development. 



The external iliac arises from the lateral side of the hypogastric and 

 is qnite independent of the segmental arterial system. It takes a longi- 

 tudinal course, crossing medial to the root of the obturator nerve in the 

 cephalic direction. During the considerable period of development which 

 precedes the origin of the femoral and inferior epigastric from it, its 

 walls become progressively thickened by condensation of the adjacent 

 mesenchyme. 



The femoral artery, when it has once appeared, very rapidly extends to 

 the popliteal fossa and there taps the ischiadic. The external iliac, on 

 the contrary, scarcely alters in appearance between the human stages of 

 8.5 and 12 mm., and between the stages in pig of 10 and 12 mm. or 

 somewhat later. 



Eeconstructions are shown of this vessel in human embryos of 8.5 and 

 12 mm. (crown-rump measurement), and in pig emb'ryo of 12 mm. 

 (greatest total length). In none of these stages is the femoral present. 

 In a reconstruction of a human embryo of 13.6 (greatest total length) 

 the femoral and inferior epigastric arteries are well developed, and the 



^ Ueber die urspriingliche Hauptsclilagadei- der liinteren Gliedmasse des Menschen und 

 der Saiigerthiere, u. s. w., Morpholog. Jahrb., Bd. 16, S. 300, 1890. 



