x VASCULAR MUSCLE AND NERVES 365 



Nothing certain is known about the anatomical and functional 

 relations which exist between the spinal vasornotor centres and 

 the bulbar centre. Certain comparative experiments of Kowalewsky 

 and Adamiik, Luchsinger, and others on the vascular effects con- 

 sequent on asphyxia in animals with intact and others with 

 divided cord lead, however, to the conjecture that the spinal 

 vaso-constrictor centres are less excitable than the bulbar centre. 

 For in curarised animals, when the bulb is cut off from the cord, 

 the rise of arterial pressure at the close of artificial respiration 

 begins and reaches its maximum, much later than in animals 

 with intact spinal cord. This leads to the view that the normal 

 tone of the vascular centre, and its rhythmical or a-rhythmical, 

 automatic or reflex oscillations, depend principally, if not ex- 

 clusively, upon the bulbar centre, which, in consequence of its. 

 greater excitability, reacts more quickly to all stimuli, extrinsic or 

 intrinsic. 



Just as there are vaso-constrictor centres below the ruling 

 bulbar centre, so it seems logical also to assume the existence of 

 vaso-constrictor centres above the bulb, i.e. in the brain. But the 

 experiments adduced in this connection give no convincing 

 evidence in favour of such a hypothesis, since they are susceptible 

 of various interpretations. Excitation of the cerebral peduncles 

 in curarised animals is followed by a pressor effect (Budge) ; on 

 stabbing the anterior or posterior corpora quadrigemina, vaso- 

 constriction followed by dilatation is obtained (Eckhard) ; if the 

 corpora striata or the internal capsule are electrically stimulated,, 

 there is rise of arterial pressure (Danilewsky and Strieker) ; when 

 the cortex, particularly in the region of the so-called motor zone, 

 is electrically excited, a more or less distinct pressor effect ensues, 

 even if no epileptic fit is set up (Danilewsky, Bochefontaine, 

 Richet, Franc, ois-Franck and others). These phenomena may be 

 explained in the sense that there are no true vaso-constrictor 

 centres in the cerebrum, but only simple nerve paths, which throw 

 the bulbar vasomotor centres into activity, like the afferent 

 peripheral nerves. The effects of lesions in these parts, however, 

 seem to witness more than those of stimulation to the presence 

 of true vaso-constrictor centres in the brain. 



After circumscribed extirpation of certain points upon the 

 cerebral cortex in the region of the motor zone, a marked and 

 fairly protracted rise of temperature in the hind-limbs has been 

 observed (Eulenburg and Landois) ; in clinical paralysis from a 

 variety of central lesions the same effect may be observed in the 

 paralysed limbs, as well as ecchymosis in different organs, notably 

 in the lungs and joints (Charcot and others). 



VIII. We have fewer data in regard to the localisation of the 

 vaso-dilator centres in the several parts of the central nervous 

 system. It seems highly probable, however, that they are no less 



