374 D. OGATA AND SWALE VINCENT 



small number of sensory nerve fibers. If the stimulation of a 

 few fibers be the equivalent of a weak current, the fall of blood- 

 pressure caused by stimulating the nerve terminals may be 

 ascribed to the fact that we are stimulating only a few fibers. 



Under morphia and curare a rise of blood-pressure is more 

 easily obtained than a fall on stimulation of nerve-endings. 

 But under morphia at any rate it is not difficult to obtain a rise 

 with a strong stimulus and a fall with a weak one (fig. 19). 

 GaskelFs^ discovery that in mammals ''A large dose of curare 

 will remove both the contraction of the muscle and the dilatation 

 of its blood-vessels upon stimulation of the nerve," may possi- 

 bly account for the greater tendency towards a rise when the 

 animal is under this drug. 



The paralysis of the vasodilator nerves by curare seems to 

 necessitate the taking of certain precautions in interpretation 

 of the results of experiments. 



It seems probable that if it were found possible to increase 

 very considerably the energy and extent of the stimulation in 

 the cases of kneading of muscle and of the intestine, we should 

 have to record a rise of pressure instead of the fall with which 

 we are familiar. 



7. THE INFLUENCE OF THE DUCTLESS GLANDS UPON VASOMOTOR 



REFLEXES 



The extracts of some of the ductless glands (adrenal body, 

 thyroid, and pituitary) have been alleged to affect the vaso- 

 motor irritability on one way or another.^^-'^^-^^'^'^* Since the 

 results of the previous investigations are not conclusive, we 

 thought it might be worth while to investigate the matter 

 again. It is to be feared that our experiments are not much 

 more convincing than those of previous workers on this subject. 



The change of blood-pressure (augmentation or diminution) 

 due to the injection of the extracts of these glands is an undesir- 

 able complication. In cases where an augmented blood-pres- 

 sure is the result, as with adrenin and pituitrin, the decreased 

 pressor reaction to the stimulation of a nerve may most properly 

 be ascribed to the diminished response of the already more or 



