CARDIOVASCULAR CHANGES DURING CEREBRAL ANEMIA 13 



It is interesting to note, however, that when the animal is no longer 

 intact, and the peripheral resistance has been markedly lowered by a 

 high transection of the cord, these relations are changed. Yates (36) 

 has observed that cats which showed a considerable anemic rise after 

 recovery from such a section, completely lost their ability to react to 

 cerebral anemia following a subsequent excision of the stellate ganglia. 

 However important for all practical purposes the vasomotor control 

 may be, the considerable involvement of cardiac factors in the inte- 

 grated response, particularly in the event of injury to the vasomotor 

 nerves, must not be overlooked. 



c. Influence of the splanchnic nerves on the anemic rise. The wide 

 distribution of the splanchnics, gives a possibility for various lesions 

 within the system. Section of the splanchnics was therefore undertaken 

 1, in the base of the sympathetic chain before leaving the thorax; 2, in 

 the abdomen, just prior to their entrance into the coeliac ganglion; 

 3, in various levels of the spinal cord in the thoracic region. 



The anatomical relations of the splanchnic outflow in the cat have 

 been described by Langley (64), who concludes that the fibers destined 

 to enter the splanchnic nerves leave the cord in large part below the 

 level of the sixth thoracic, though occasionally fibers can be traced at 

 the level of the fifth and even fourth thoracic. Langley's statement 

 appears based only in part on his own observations, and is largely 

 founded on the work of other investigators embodied in the papers 

 quoted. Several authors included higher levels for the effects studied 

 based on experimental rather than anatomical evidence though all 

 have stated that the effect elicitable is relatively slight. Bayliss and 

 Starling gave 3rd thoracic as supplying the portal circulation, Bradford, 

 the 3rd thoracic as supplying the kidney; and Schafer and Moore, 

 3rd thoracic as supplying the spleen. 



In a more recent study on cats Ranson (65) has re-investigated the 

 problem. He confirms Langley's findings and considers the 4th thor- 

 acic the highest limit of the splanchnic outflow. Ranson's material, 

 however, was in part restricted to animals in which only the levels 

 below the 6th thoracic were examined. Ranson has investigated fur- 

 ther the level at which the splanchnic nerve leaves the sympathetic 

 chain. In far the greater number of cases (13 out of 17) the nerve was 

 given off between the 1st lumbar and 13th thoracic ganglion, in the 

 remaining four cases, the nerve left between the 1st and 2nd lumbar 

 ganglia. The relation of this branching to the diaphragm was not 

 stated. 



