80 Scientific Proceedings (48). 



is not very prompt we might expect that the intraspinal injection 

 of adrenalin will have no stronger effect upon the blood pressure 

 than that of a subcutaneous injection. We studied this question 

 experimentally and may say at the outset that our results did 

 not bear out this anticipation. Our experiments were made 

 on six monkeys, using each monkey two or three times. The 

 amount injected was either 1 c.c. or 1.5 c.c. of the commercial 

 adrenalin. Most of the injections were made in the lumbar 

 region; but in a few instances the adrenalin was injected in the 

 thoracic region in the fifth intervertebral space. During the 

 experiments the animals were under fairly profound anesthesia 

 and we are unable to state whether the injection had any other 

 effect besides the change in the blood pressure. But it is impor- 

 tant to point out that even doses of 1.5 c.c. of adrenalin had no 

 recognizable after-effects upon the animal. 



The action upon the blood pressure was in most cases very 

 characteristic. The pressure would begin to rise slowly but 

 steadily, so that in a few minutes it would reach a maximum 

 varying between 150 and 190 millimeters, and would then com- 

 mence to go very gradually down. As a rule the entire course 

 of the rise lasted longer than in intravenous injections, in some 

 instances even longer than half an hour. The fall of blood 

 pressure occurred so slowly at times that the original level was 

 not reached during the entire time of observation, a fact which 

 might be of considerable practical importance. 



Twenty-one injections were given to these six monkeys at 

 intervals; of these thirteen gave the typical rise described. In 

 six cases the rise was preceded by a moderate fall (9-52 mm.) 

 of short duration (H~4 minutes) and in one case this fall was 

 the only effect of the injection. In the seven instances the injec- 

 tion brought on a rise similar to that of an intravenous injection 

 but of longer duration. It is possible that in these cases part 

 of the injection entered indeed into a vein. 



