168 KANSAS UNIVERSITY QUARTERLY. 



At the base of the skull communicating branches exist be- 

 tween the spinal plexuses and vena vertebralis. The latter, 

 in turn, connects through the superior intercostal with the 

 azygos directly, or when the vertebralis and the superior in- 

 tercostal are both connected with the innominate, then indi- 

 rectly through it. 



From the posterior region, the blood reaches the azygos 

 through vessels from the muscles and w^alls of the sacral and 

 lumbar regions that enter the spinal plexuses, and through the 

 three commonly four-forked lumbar veins, which furthermore 

 establish circulation between the postcava and azygos, when 

 the latter arises from a network or longitudinal vessels connect- 

 ing the lumbar with each other and the spinal veins, or directly 

 from one of the lumbar veins. 



At the first lumbar vertebra, the azygos possesses a valve and 

 enters a foramen, presenting the appearance of suddenly com- 

 ing to a limit. It receives, however, among others, tributaries 

 from vessels of the diaphragm, adrenal, ileo-lumbar, inter- 

 costal, and often a large vein from the first lumbar. 



It is evident that the postcava and azygos are mutually de- 

 pendent and supplementary, and that if for any cause the post- 

 cava should be obstructed anywhere in its course, the blood 

 would be returned to the heart by the azygos through the inter- 

 vention of the lumbar veins and spinal plexuses. The latter 

 practically establish communication between veins of the body 

 throughout the. extent of the spine. 



It was of interest to test the correctness of this assertion ; 

 then, too, the facts connected with such an operation seemed 

 sufficiently important to warrant its undertaking. 



The first experiments were performed on kittens two days 

 old. It was thought that animals at this period of growth, 

 with immature arrangement of vessels connecting with those of 

 the liver, would more readily adapt themselves to the altered 

 conditions introduced by the experiment. On the other hand, 

 the chances of keeping them alive are lessened even by feeding 

 them with warm sterilized milk. In regard to this question, 

 however, too few operations were made on such young kittens 

 to justify drawing a definite conclusion. 



From a litter of four kittens three days old one was kept for 

 a control experiment; the remaining three were auciesthetized, 



