APn 34 1901 



KAxNSAs university Quarterly. 



Vol. 9. No. 3. JULY, 1900. Series A. 



• COLLATERAL CIRCULATION IN THE CAT AFTER 

 LIGATION OF THE FOSTCAVA. 



BY IDA H. HYDE. 

 With I'late XXXVI. 



In a thesis written in 189 1,* I compared the azygos venous 

 system of lower animals with that of man. It was held, at that 

 time that the azygos vein in the cat could not be traced beyond 

 the diaphragm. In a chapter relating to the venous system, it 

 is true, St. George Mivart, in his "Anatomy of the Cat," says 

 that '"'the distribution of the azygos vein in the cat is the same 

 as that in man." This statement is incorrect, as can be readily 

 seen by the dissection of more than one cat, for that animal 

 possesses only a right azygos, which, differing in its distribution 

 more or le^s in almost every cat dissected, does, as my work 

 proved, and is now stated in the last edition of Wilder and 

 Gage's Anatomical Technology and other revised editions of 

 anatomies, arise in the lumbar region. 



The azygos vein and its branches constitute a system of great 

 importance. It assists in maintaining the circulation through 

 the spinal plexuses, and not only forms a connecting link be- 

 tween the pre- and postcava, but can, as I shall show, main- 

 tain, if necessary, the circulation of the blood throughout the 

 body when the postcava, from pathological or other causes, is 

 prevented from sending its blood into the heart. Inasmuch as 

 the azygos distribution has not been described in detail in any 

 of the text-books, I shall state its distribution in the briefest 

 manner, to aid in a better understanding'of its relation to the 

 venous system. 



L *Now in the library of Cornell University. 



12-K.U.Qr. A-ix3 [167J-K.U.Qr.-A ix 3-Jul.v, 'CO. 



