356 D. OGATA AND SWALE VINCENT 



and Quinby^^ say: "It is sometimes urged that in shock the 

 blood-pressure falls instead of rising on stimulation of afferent 

 nerves. This abnormal reaction was observed in several of our 

 experiments." This statement clearly involves the assumption 

 that a rise is the normal effect, though it is recognized that the 

 fall is a not very unusual occurrence. Vincent and Cameron'*^ 

 seem to be of opinion that the usual effect of stimulating the 

 central end of the cut sciatic nerve is a rise, and the fall due to a 

 pure vasomotor reflex is rather rare. So also Hunt. On the 

 other hand, Martin and Lacey^^ having observed regularly a 

 definite drop in blood-pressure by weak stimulation and a rise 

 by far more strong stimulation, became doubtful of the truth 

 of the generally accepted doctrine that pressor responses are the 

 normal results of sensory stimulation. 



These differences of opinion must be due to some factor or 

 factors other than the strength of stimulus. Besides the fac- 

 tors most usually considered, such as different modes of stimu- 

 lation, different nerves, different conditions of the same nerve, 

 different narcotics, drugs, etc., there are two important consid- 

 erations recently brought fo*rward which unmistakably affect 

 the vasomotor reflexes or complicate the problem of their 

 elucidation. 



In 1915 Vincent and Cameron"*^ called attention for the first 

 time to a fall of blood-pressure caused by increased respiratory 

 movements. They write: "While anaesthesia is fairly complete 

 the effect of stimulating the central end of the cut sciatic nerve 

 is a pure and distinct rise. As the effect of the anaesthetic be- 

 gins to pass off, the effect of stimulation will be a rise of blood- 

 pressure followed by a more or less pronounced fall. Respira- 

 tory movements will now be found to have been markedly in- 

 creased, and the extent of the fall of pressure appears to be at 

 any rate proportional to the violence of the respiratory activity." 



Martin and Lacey^' investigated the influence of the inter- 

 ruption of the primary current at widely varying rates, but 

 failed to notice any effect, as also did Hunt^^ in his earlier work. 

 Only quite recently it was clearly pointed out by Gruber^ that 

 with the same strength of stimulus, pressor and depressor results 



