B 



C 



D 



Fit;. 246. LOYEN KEFLEXES. 



A, I'pper curve, blood pressure. 



Lower curve, volume of upper part of hinrl leg of dog. 



At the signal, the central end of the dorsalis pedis nerve of the same leg was stimulated, causing a 



slight fall of blood pressure, with marked dilatation of the leg. 

 Note that the usual effect of a sensory nerve is to cause reflex vaso-constriction in the body generally. 



B, Upper curve, blood pressure. 



Lower curve, drops of blood falling from cut femoral vein. 



At the signal, the central end of the anterior crural nerve of the same leg was stimulated. A rise of 

 blood pressure is seen, accompanied by dilatation of the leg. Fig. 239 shows that stimulation 

 of a sensory nerve from another region, "namely, the median of the arm, causes vaso-constriction 

 in the leg. This fact is also shown in 



C, Upper curve, volume of hind limb of dog. 

 Lower curve, blood pressure. 



Vaso-dilators cut off by section of the lumbar and sacral dorsal roots. 

 At the signal, the central end of the median nerve was stimulated. 

 The rise of pressure is accompanied by constriction in the leg. 



D, Same experiment, but instead of the median nerve, the central end of a sensory root of the leg 



area, namely, the sixth lumbar dorsal root, was stimulated. 

 Again there is the usual rise of general blood pressure, but the vessels of the limb itself dilate 



considerably. 



This experiment shows that in the I.<*v on reflex there is inhibition of constrictor tone, and the proof 

 is given in Fig. 9 of my paper of 1902, 3, that the dilators are excited, so that reciprocal 

 innervation holds in this case. 



(C and D from Bayliss, 1908, 2, Fig. 8.) 

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