86 



Scientific Proceedings (64). 



was much more difficult to confine the blood pressure to the 

 desired level. 



Comparing this series with the control series, and bearing in 

 mind the modifying considerations which have just been men- 

 tioned, the conclusion is justified that little additional shock- 

 producing effect was produced by the electrical stimulation of the 

 peripheral sensory nerves. This conclusion is further strengthened 

 by the results of the second series of stimulated animals. These 

 animals were subjected to electrical stimulation during a period in 

 which their blood pressure was reduced to a level which was con- 

 sidered safely above the critical level of the controls, namely, 40 

 to 50 mm. Five of these experiments were performed and all ani- 

 mals recovered. 



In two of them the pressure was held between 40 and 50 mm. 

 of mercury; 



In one, between 40 and 60 mm. of mercury; 



In two, between 50 and 70 mm. of mercury. 



The results of this series still further emphasize the conclusion 

 that the reduction of blood pressure is the all-important factor in 

 the death of these animals, and that even in animals made very 

 sensitive to shock-producing influences by a reduction of their 

 blood pressure, the additional influence of trauma to the periph- 

 eral sensory nerves, as a factor in the death of the animals, is a 

 small one. 



In five other similar experiments, an attempt was made to 

 compare the medullary reflexes at the end of the experiment with 

 those at the beginning. In two instances, no increase of the stim- 

 ulus required to elicit the cardio-inhibitory reflex from central 

 stimulation of the vagus was necessary at the end of the experi- 

 ment, as compared to the strength of the stimulus required at the 

 beginning of the experiment. In three experiments, such a slight 

 increase was required that it was considered negligible. 



