igoo-i.] 



Observations on Blood Pressure. 



197 



Tracing 16 shows the carotid blood pressure 

 occurring in a dog in which the spinal cord had 

 been divided near the eleventh dorsal vertebra. 

 In this case the pulse increased greatly in rapidity 

 as the pressure fell on the animal being placed vertical 

 at 27. The animal was kept in the feet-down position 

 for some minutes without any appearance of compen- 

 sation occurring, and was placed horizontal again at 

 29. Now the vaso-motor fibres for the splanchnic 

 nerves leave the cord above the level of the eighth 

 dorsal nerve ; the section in this experiment took 

 place well below this, and thus the vessels of the 

 splanchnic area were not paralysed by the operation, 

 yet a very marked fall occurred. This would point 

 to the fact that the vessels of the lower part of the 

 body are very largely concerned in the keeping up of 

 the normal blood pressure in the feet-down position, 

 because when they are paralysed the pressure 

 markedly falls. 



