MOVEMENT OF THE BLOOD IN THE ARTERIES. 327 



traction of the minute arteries on that side of the face, which can be well 

 seen in those distributed to the external ear of the cat or rabbit. As in the 

 case of the Heart, the nerves supplying the bloodvessels appear to have two 

 centres, one of which is represented by the small ganglia distributed in the 

 walls of the vessels, whilst the other is represented by a centre or a series of 

 centres, situated in the medulla oblongata and spinal cord. The activity of 

 the local ganglia is rendered evident by the contractions that may be produced 

 by direct irritation after division of all the nerves supplying a part. The 

 a nfri// ganglia governing the contraction of the vessels have received much 

 attention during the last few years, 1 the general result of which has been to 

 show that an important centre is situated in the medulla oblongata, its lower 

 limit in rabbits being about one-eighth of an inch above the level of the apex of 

 the calamus scriptorius, whilst the upper limit is near the upper border of the 

 corpus trapezoides, just below the corpora quadrigemina (Ludwig and Thiry, 

 Owsjannikow and Dittmar). It occupies the autero-lateral part of the medulla 

 oblongata on each side, and corresponds to the continuation through the me- 

 dulla oblongata of the anterior part of the spinal cord. Browu-Sequard, 2 

 Goltz, and others have pointed out that in some animals (Dog) the vaso- 

 motor centre or centres must extend for some distance down the spinal cord, 

 since on division of the cord in the cervical region, which is followed by 

 general dilatation of the vessels of the body, section of such a nerve as the 

 sciatic is followed by still further dilatation of the vessels of the posterior 

 limbs accompanied by elevation of temperature. [Schlesiuger 3 found that 

 after section of the spinal cord in the neck, strychnia elevated the blood- 

 pressure very decidedly. He also established that it was due to an irritation 

 of the vaso-motor centres situated in the cord. Under the direction of Dr. 

 I. Ott, Dr. W. H. Klapp has experimented on cats, and seen a similar rise of 

 pressure in the Physiological Laboratory of the University of Pennsylvania.] 

 Some experiments of Cyon seem also to show that the vaso-motor centre ex- 

 tends into the brain above the plane of the medulla oblongata ; still the most 

 important centre is certainly placed in the medulla oblougata. This centre 

 exercises a permanent tonic influence on all the smaller vessels, and especially 

 upon the smaller arteries of the body, maintaining their muscular fibres in a 

 state of general contraction. It receives centripetal or afferent, and gives off 

 efferent or centrifugal fibres. Both sets of fibres, as Miescher 4 and Na\vrocki a 

 have shown, run in the lateral columns of the spinal cord, and enter into or 

 issue from it with the roots of the several spinal nerves, at least as low down 

 as the eleventh dorsal nerve. They run partly in the sympathetic cords, 

 and partly with the branches of the spinal nerves. Thus the cervical cord 



1 Wiener Sitz -her., Bd. xlix, and Zeit. f. Kat. Med., Bd. i. For other papers on 

 the influence of the nerves on the bloodvessels, see besides many of those mentioned 

 in the note on p. 316, the essays of Ludwig in conjunction with Cyon, Loven, Asp, 

 Hah'z, Owsjannikow (1871), and Dittmar (1873), in Lud wig's Arbeiten, 1866-73, und 

 Berichte der Sachs. Gesell., 1866-71. Also the papers of v. Bezold in conjunction 

 with Stezinsky, Bever, Breymann, Dreschfeld and Gescheidlcn, in the Untersuch. 

 RUS der Physiol. Labor, zu "VViirzburg ; Heidenhain, in Pfluger's Archiv, Bd. iii, 

 iv, and v. ; Rover, N erven einfluss auf. d. Gcfasse, 1869; Thiry and Kowalewsky, 

 Centralblatt, 1868, p. 579; Saviotti, Virchow's Archiv, Bd. 1, 1870, p. 592; Budge, 

 Pflujrer's Archiv, 1872, p. 303; Goltz, Pflugcr's Archiv, Bd viii, p. 460; Putz<>ys 

 and Tarchanoff, Centralblatt, 1874, p. 641 ; Putnam, Boston Med and Surg. Journal, 

 1870, p. 4G9. 



2 Journal de la Physiologic, t. i, 1858, p. 209. See also Vulpian, Lepons sur 

 1'Apparcil Vaso-moteur, 1875, p. 266; and Cyon, Hemrnungen und Erreg, in Central 

 Syst. d. Geiiissnerven, Bull. d. Petersb. Akad., Bd. xvi, p 97, and Centralblatt, 1871, 

 p. 407. 



3 [Wiener Med Jahrbuche, 1874.] 4 Ludwig's Arbeiten, 1870, p. 172. 

 5 Idem, 1871, p. 89. 



