360 KUPTUEES OF THE HEAET. 



interspace between the first and second cervical vertebrae. 

 He first observed, as the thorax was opened, circumscribed 

 plots, between the pleura and vertebrae, covering the azygos 

 vein ; the blood sometimes trickling down beneath the serous 

 membrane. On dissection, jagged ruptures of the blood- 

 vessel were discovered. His friends, Professors Maffei and 

 Balboni, having sought from him an explanation of the fact, 

 he suggested (to my judgment very plausibly), that the instant 

 the animals are pithed, the walls and contents of the thorax 

 are paralyzed, the heart becomes an inert bag filled with 

 fluid, the jerk of which, as the animal falls, causes rupture of 

 the containing vessel at its weakest part; and this is, in 

 truth, the vena azygos, whose walls are thin, and only pro- 

 tected externally by the pleura. At my brother's suggestion, 

 Professor Maffei instituted a series of observations to deter- 

 mine the frequency of the lesion under consideration ; and 

 with his customary courtesy and exactness thus communi- 

 cated the result: 'From the 1st of June 1854, to this date 

 (28th May 1855) 3095 oxen and cows were killed in our 

 public slaughter-houses ; I have met with the rupture of the 

 azygos in fifty-seven of these animals ; these ruptures occur 

 in various parts of the said vein ; at times where the inter- 

 costals join it, and at other where the vein curves round to 

 empty itself into the anterior vena cava. Such lacerations 

 seem to occur about the same number of times in either of 

 these situations: they bear the character of regular tears, 

 inducing an effusion of blood between the laminae of the 

 mediastinum, or beneath the parietal pleura. Sometimes the 

 vital fluid flows into the thorax itself 



" Taking these facts into consideration in connection with 

 those recorded in the appended tabular exposition of cases, 

 the mechanism of these lesions seems to admit of two- 

 fold explanation. Istly, In the case of a person falling 



