450 



It is bj no means uncommon to find the vena azygos major, 

 suspended by a " mesentery " of pleura, lodged in a groove in the 

 lung and cutting off the mass of lung substance called Wrisberg's 

 lobe. This abnormality has a wide range of variation. In its most 

 complete form the mesentery of the azygos vein has its attachment 

 to the parietal pleura approximately along the line of the first rib 

 (Fig. 2). In such circumstances the apex of the lung is bifid (Fig. 3). 



In any case of this 

 type inflammatory proces- 

 ses may lead to the replace- 

 ment of the apical pleura 

 by fibrous tissue. In ex- 

 treme cases the existence 

 of the pleural "mesentery" 

 may be lost in a mass of 

 fibrous tissue binding 

 Wbisberg's lobe and the 

 lung apex together and the 

 azygos vein may then appear 

 to emerge from the lung 

 and may readily be supposed 

 to come from the lung sub- 

 stance — in other words to 

 be a pulmonary vein. The 

 mistake is the more liable 

 to occur if dense adhesions 

 surround the point at which 

 the azygos vein enters the 

 lung substance. This false 

 type of " pulmonary " vein 

 entering the superior vena 

 cava is therefore the result 

 of a pathological acquire- 

 ment superadded to a con- 

 genital variation. A case of 



Fig. 1. Photograph to show heart and great 

 vessels of a case in which four right pulmonary 

 veins open into the superior vena cava which in 

 turn opens equally into the right and left auricles. 

 The crescentic upper margin of the inter-auricular 

 septum is seen stretching across the mouth of the 

 superior vena cava. 



this type has recently been 



observed in this laboratory. 



To find one or more true pulmonary veins opening into the 



superior vena cava is not very rare for pulmonary veins may open 



