5Q 



Scientific Proceedings (62). 



abdominal viscera, and by applying cold water. When the blood 

 pressure had fallen to a low level, e. g., 19 to 25 or 30 mm. Hg., 

 the normal ear, that is, the ear still connected with the vaso-motor 

 center was practically always blanched and bloodless. Even with 

 this low blood pressure, however, the vessels of the denervated 

 ear, contained in most cases, definitely though, as would be 

 expected with low blood pressure, slightly more blood than the 

 normal ear. If at this stage a clamp was applied to the abdominal 

 aorta just below the diaphragm the blood pressure in the anterior 

 portion of the body usually rose quickly to a relatively high level, 

 for example, from 18 mm. Hg. before clamping to 75 or 85 mm. 

 Hg. afterward. With this rise in blood pressure there developed 

 a striking contrast in the appearance of the two ears. The vessels 

 of the denervated ear become gorged with blood, while the vessels 

 of the normal ear in almost every case remained practically 

 maximally constricted. If the connection of the vessels of the 

 normal ear with the vaso-motor center was severed, either by 

 cutting the nerves, destroying their conductivity by the local 

 application of ether, or by freezing the nerves with ethyl chloride, 

 the vessels of the normal ear also became widely dilated. 



These experiments have shown that at the time when the 

 rabbits were apparently deep in shock the vaso-motor center was 

 not only not paralyzed but was maintaining a tonus in the vessels 

 of the normal ear of sufficient strength to prevent dilatation of 

 these vessels if the blood pressure was raised to 75 or 85 mm. Hg. 

 or in some cases even higher. 



