Congenital Anomalies of Arteries and Veins 47 



(1881), Nicolai (1887), Sperino (1887), Josselin (1893). MoUi (1893), 



Delia Rovere (1897), Deve (1899), Fischer (1899), Maussert (1899), 

 Sejour (1904), Bluntschli (1905), Dufour (1905). 



Other anomalies of the Azygos are: Stark (1835), Bastein (i860), 



Collins (1873), Morison (1878), Brooks (1885), Humphrey (1885), 



Martin (1897), Delia Rovere (1897), Freyberger (1898), Heller (1908), 

 Anikiew (1909), Holtby (1914). Sabin (1914)- 



\rENA CAVA INFERIOR 



The variations which the inferior vena cava presents may be 

 explained from an embryological standpoint by referring to the 

 data on the rabbit and pig presented by Hochstetter (1887), Lewis 

 (1901), and Davis (1910). Lewis conckides that the adult in- 

 ferior vena cava is formed from the heart, hepatic vessels, upper 

 part of the subcardinal vein, and lower part of the right cardinal 

 vein ; he also considers that the left cardinal vein is represented in 

 the ascending lumbar vein. Hochstetter thinks that this latter is 

 a secondary anastomosis. 



The most frequent anomaly consists of the persistence of the 

 portion of the left post-cardinal vein which usually atrophies ; a 

 list of such general anomalies will conclude the section. In most 

 of these irregularities where the right subcardinal vein has failed 

 to establish connections with the hepatic the renal vein passes dorsal 

 to the aorta, Cruveilhier (1832), LaGendre (1859), Hochstetter 

 (1893), Kollmann (1893), Kaestner (1900), D wight (1901), 

 Gladstone (1911), Johnston (1912). 



Preaortic anastomosis indicates that the anomalies are confined 

 to the post-renal segments of the post-cardinal veins, Paterson 

 (1900), Gerard (1903), Patten (1909), Frankel (1910). 



Gladstone reports the right ureter passing behind the vena cava, 

 also see Hochstetter (1894). 



Occasionally the inferior cava establishes a direct connection 

 with the superior, as in the case of Louber (1901), and more fre- 

 quently the connection is with the azygos system, Bastein (1859), 

 Bachhammer ( 1879) , Carpentier (1888) , Kollmann ( 1893) , Berens 

 (1898), Kaestner (1900), Revell (1902), Patten (1909), Alten 

 (1913), Poynter. 



A few cases are recorded in which the left cava persists and the 



