16 CORA SENNER WINK1N 



mals. In such animals the level of pressure shows similar oscillations, 

 but these vary within a much greater range, usually approaching 200 

 mm. difference in level. No recovery of bulbar functions was elicited 

 from any of these animals. That this was not the necessary conse- 

 q/uence of a lesion at this level, but merely an indication of the precarious 

 conditions of animals exposed to this double lesion, is shown in the 

 following experiments. 



Section of the sympathetic chain; abdominal section of the splanchnics. 

 Although the blood pressure response is. seriously reduced by section 

 of the splanchnic nerves above the diaphragm, a slight degree of re- 

 sponse still seems elicitable. It seems possible, however, completely 

 to eliminate all rise of blood pressure as the result of bulbar anemia, 

 while maintaining all other evidence of medullary activity, by section of 

 the greater splanchnic nerves in the abdomen. 



Dissection for the splanchnics in the abdomen was made 'by the 

 method indicated in Sherrington's Mammalian Physiology (66). The 

 incisions were made from the back, through the latissimus dorsi mus- 

 cles, and the nerves were cut just before their entry into the coeliac 

 ganglion. The identity of the nerves was first tested by electrical 

 stimulation with shielded electrodes. 



A striking example of the result of this section was obtained in cat 

 23. In this animal (fig. 2) the greatest excursion of blood pressure 

 amounted to 10 mm., yet all other effects of occlusion were noted. An 

 asphyxial effect on the vagi appeared in the pressure curve followed by 

 a very slight improvement in the level. From this point on, however, 

 pressure fell very gradually, until, at the end of 3 minutes, it remained 

 constant. In this very gradual fall, pressure reached a level some 

 20 mm. below that of the original pressure before occlusion. After 

 digital compression of the abdominal aorta, spontaneous respiration 

 returned in this animal. When respiration had become completely 

 reestablished and a corneal reflex again obtained, the trachea was 

 clamped. No asphyxial rise of pressure to speak of was obtained, the 

 entire subsequent variation of pressure being well within 20 mm. Hg. 

 Respiratory waves and some vagus effect were recorded; failure of the 

 heart soon followed. 



Section of the thoracic spinal cord. Section of the spinal cord was 

 undertaken in 16 cats. The laminectomy was carried out immediately 

 following tracheotomy, the wipund temporarily closed by hemostats 

 and the head arteries then prepared for ligation. Finally the cord 

 was sectioned, and blood pressure allowed to reach a constant level 



