128 



W. M. Bayliss and J. R. Bradford, 



ment, the chorda giving in this case a pure second phase (outer sur- 

 face of gland positive). Again, not only are these differences to be 

 observed in different animals, but very often they are seen in the same 

 animal, excitation of the chorda producing now a pure first phase, 

 now a diphasic variation. These differences are due in the first place 

 to the strength and duration of the stimulus employed, and secondly 

 to variations in the activity of the gland, the latter depending largely 

 on whether the gland has been previously exhausted by repeated 

 excitation, and perhaps also on the nature of the blood -supply. 



We will now consider these variations a little more in detail, the 

 following experiment illustrates one of the few cases, in which exci- 

 tation of the chorda gave a result similar to that in the dog. 



July 13. 1885. Cat, medium sized. Crura cerebri divided. Curarized. 







Position 



Sign of outer 



Extent 



Time 



Nerve stimulated 



of 



secondary 



coil 



surface of gland 



on stimulation 



of nerve 



of 



galvanometer 



deflection 



4.10 



chorda tympani 



40 millimeters 



negative 



300 



4.12 



V JJ 



40 „ 



» 



300 



4.25 



ÌÌ 5? 



40 „ 



» 



400 



4.35 



» » 



40 „ 



» 



350 



4.40 



)> » 



40 „ 



» 



300 



4.47 



>> J> 



20 „ 



j> 



off scale 



4.50 



Atropine ( 



4 milligrams) in 



jected into pleural c 



avity 



4.54 



chorda tympani 



— 



positive 



80 



5 



» » 



— 



no effect 



no effect 



The resting current (which was of course compensated) showed the 

 surface to be negative to the hilus throughout, the difference of po- 

 tential gradually increasing up to the time when atropine was ad- 

 ministered. 



In this case we see on stimulation of the chorda, an electrical 

 variation, similar to that described in the dog, easily abolished by 

 atropine and leaving after the initial action of this drug a small se- 

 cond phase which in turn is abolished by the further action of the 

 atropine. It is particularly to be noted that in this case the secretion 



