358 D. OGATA AND SWALE VINCENT 



the more the fall of pressure tended to become replaced by a 

 rise," and that the effect of artificial respiration was "a rise, and 

 not a fall, when the animal was mider curare," i.e., when a stop 

 was put to the spontaneous respiratory movements. Thus the 

 fall of blood-pressure as a result of increased respiratory move- 

 ments seems to have been sufficiently established. 



By the majority of previous observers curare was thought to be 

 an indispensable drug in the study of the problem of vasomotor 

 reflexes, with or without any consideration of its action on the 

 vasomotor center itself. But we know that narcotics and other 

 drugs are not always free from influence upon these reflexes, as 

 pointed out by various previous investigators,^* ^^-^ and, there- 

 fore, in experimental work they should be reduced to as few as 

 possible or altogether eliminated (Vincent and Cameron). The 

 change in character of the respiratory movements, especially 

 their increase, becomes thus an almost unavoidable complica- 

 tion in the study of vasomotor reflexes when curare is not used 

 and the narcosis is not deep enough. If this complication be 

 left out of consideration, erroneous conclusions may be reached. 



Since the appearance of Vincent and Cameron's paper several 

 writers have referred to the influence of the increased respiratory 

 movements. Unfortunately, they are not in complete harmony 

 with one another. Ranson and Billingsley^^'^^ say, ''With 

 stronger stimulation the greatly increased respiratory movements 

 may no doubt play an important part in the drops in blood- 

 pressure," but Gruber and Kretschmer^ write that their ''ex- 

 periments do not support Vincent and Camerofi's theory that the 

 fall in blood-pressure is brought about by movements of respi- 

 ration which interfere with the heart's activity." This latter 

 statement seems to deny definitely the respiratory role upon 

 blood-pressure. Vincent and Cameron did not positively deny 

 that there is a true vasomotor fall of blood-pressure under cer- 

 tain conditions as a result of central stimulation of afferent 

 fibers. But they insisted, and rightly, too, that many apparent 

 vasomotor falls are really due to increased respiratory move- 

 ments. We shall see later that the fall of blood-pressure with 

 weak stimuli is a commoner occurrence than Vincent and 



