THE ACTION OF VENOMS UPON ARTERIAL PRESSURE. 101 



REMARKS. 



Experiment No. 42. 



Normal 



Time : 

 min. sec 



10 

 30 

 00 

 00 



00 



8 00 



11 00 



14 00 



19 00 



Pressure 

 m. m. 



56 

 60 

 56 

 52 

 48 

 48 

 52 

 58 

 60 

 62 



Injected 0.006 gram. 



Dead. 



REMARKS. 



Injected intravenously 0.003 gram dried venom of the Cobra 

 dissolved in 1 c. c. distilled water and a few crystals of 

 sodic chloride and filtered. 



Animal killed by pithing. 



To recapitulate the actions of pure venoms upon the arterial pressure we find 

 that the injection of venom subcutaneously causes a progressive fall of blood 

 pressure ; Avhen injected intravenously, there is a sudden and decided fall of 

 pressure, which may be immediately followed by death, or by a gradual rise, to 

 be in turn succeeded by a decline with feeble pulse as death approaches. In the 

 Cobra there is a tendency to a rise of pressure, which may go above the normal as 

 death appears. 



After section of the pneumogastric nerves and its depressor fibres we find no 

 alterations in the results obtained in normal animals, but when section of the 

 cord is made in the middle or upper cervical region by which the vaso-motor centres 

 in the medulla oblongata are practically destroyed, or when accompanying this 

 section the nerves in the neck and the spinal cord in the middle cervical region 

 are also cut, thus practically isolating the vaso-motor centres in the medulla and 

 cutting off all central nervous connection with the heart, we find that the primary 

 profound diminution of pressure is not so marked. There may even appear to be a 

 slight tendency on the part of the arterial pressures to rise above the normal just 

 before death. Even after section of the spinal cord, as above, we find in Cobra 

 the increase of pressure occurring before death as in normal animals. 



These results indicate that the primary positive failure of pressure is due chiefly 



