14 CORA SENNER WINKIN 



1. Lesions within the splanchnic outflow: Section of the sympathetic 

 chain; thoracic section of the splanchnics. In 12 animals the splanchnic 

 outflow was interrupted in the lower thorax. Under artificial respira- 

 tion, a low midventral incision was extended bilaterally on either side 

 of the diaphragm, and the lungs held back while the sympathetic chain 

 was isolated and sectioned. 



Section of the sympathetic chain below the level of the 8th or 9th 

 thoracic vertebrae usually gives a very marked fall of pressure. 

 When the splanchnic branch from the sympathetic chain itself is cut, 

 this depression amounts at least to 80 mm. Hg. In spite of this low 

 level of pressure, spontaneous respiration is not usually lost, and w r hen 

 ether is reduced, eye reflexes and other skeletal responses are readily 

 elicitable. The condition of the animal, however, is precarious, and 

 prolonged operative manipulations with too great a depth of anes- 

 thesia will readily cause complete loss of the bulbar responses. This 

 precarious .condition is in fact met with in all extended lesions within 

 the splanchnic system, and offers some difficulty in the further manip- 

 ulation of the animals. 



Occlusion of the head arteries in this series generally gave a relatively 

 vigorous response. The intensity of the response varied, the degree 

 of variation from the normal being dependent apparently on the nature 

 of the lesion. 



Group I. In these animals section of the sympathetic chain was 

 undertaken in its lower levels, post-mortem examination showing no 

 lesion above the level of the 8th thoracic. In two of these animals 

 autopsy showed the lesion incomplete on one side, thus amounting 

 largely to a unilateral injury. The anemic response obtained in four 

 of these animals was very considerable, the values being 100, 120, 140, 

 150 mm. Hg., respectively. The contour of the curves was typical of 

 the normal anemic responses, and the rise of pressure easily over-reached 

 the original control level of blood pressure. All these cats showed a 

 normal recovery from the occlusion. In nos. 12 and 15, excision of the 

 stellate ganglia was done subsequent to recovery and a third occlusion 

 obtained. Cat 15 that had shown an unusually vigorous response in 

 its first occlusion gave an increment of 125 mm. Hg. after excision of 

 both vagi and both stellates. The thoracic chain was sectioned at the 

 level of the 8th and 9th thoracic on one side, between the 10th and llth 

 on the other. Cat 11 was slightly different. The original depression 

 of blood pressure after section of the chain was 80 mm. Hg.; the anemic 

 increment was somewhat reduced, amounting only to 70 mm. so that 



