54 



I I- r K R 



tluToforc in iicrord, and indir.itr that the cliirf vasomotor centre is in ilie nu-didhi 

 oblongata, probably in the exact position indicated by Owsjannikow. 



It is true that Prof. C'yon {Mi'Utiujtn JHoIojujiuh tiiiH du liulUtin di I' Antdi'mie 

 Jinjii'rUde dtti iicU'inc'i dt; tSt. I'lh i-iiL)urij, t. vii.) found that wln-n the cerebral 

 hcuiispheri'S are removed, the medulla oblongata and tlie ccrebellnni btiug IcI'i un- 

 harmed, irritation of a sensitive nerve is not followed by a rise of arterial pressure. 

 The shock and the bleeding from such an operation arc, however, so great that the 

 n-sultsof the experiments are of little value; certainly the loss of blood and the nervous 

 disturbance might very conceivably of themselves paralyze the vaso-m<»tor centres, 

 or their controlling intluence, if tliesc latter were in the medulla oblongata, 

 riierefore it cannot be allowed that the experiments of I'rof. t'yon really con- 

 tradict those which have just been cited. 



Itecently the correctness of the conclusion of Dittmar and his corroborators has 

 been further called in question (I)upuy, TraiiKnvdoas A)ii< riaiii Xvinoli);/. Sfc'tity, 

 IMm), anil it seems therefore necessary to report the following records of experi- 

 ments which entirely confirm those of Uittmar, Owsjannikow, and Ileideidiain, and 

 which demonstrate that tlie chief or governing vaso-motor centre is situated in 

 the lower part of the fourth ventricle. 



PLXPERIMENT 40. 



A stoDt dop. Mfdiillii cut, piii'lunognstrics severed nt 12:20 p. M. 



12:.'{0 !'. M. — Arterial |iressiiro 120. On palvniiizing a sensitive nerve tiie |ire.->tiie nt first fell, 

 but soon rose to isf), nltli'mpli there were no convulsions or muscular uioveiuents except in the few 

 roasclcs directly tributary to the nerve. 



Autopity. — Medulla nearly severed obliquely nt its junction witii the pons. 



Experiment 41. 



A terrier. 



IrS.") p. M.— Section made; nt .T p.m. the aniinnl breathing quietly, the carotid was connected 

 with llio manometer, nn<l tiie sciatic nerve exposed. 



TiHi. ArrrnrAL Pnoxrr.i:. IniiiTATio!i. REMARKS. 

 iMllllmrlro.i 



M. Oll-lno* 



IMl-ino Itcgnn. 



3:10 125-120 Ccoscd. 



3:1C Par vapmn cut. 



351 Ch-9i 



1 fiS-W n.'L'an. 



120-12.5 t'caiii'il. No convnlflivc movements hove lieon prodnrerl by the rurrrnt fl- 



cept in the distal niti.'ieles supplied by the nerve. 



Aiilnpmj. — Right half of medulla completely separated nt its junction with the pons excepting* 

 Bninll band on each side; left side cut through except a narrow band at the outer edge. 



• Tlie pressure experiments reported in thi.s paper are all of them relative experiments; the gr«d«- 

 • are in millimetres, but the zero in different in different experiments, always, however. I>emg 



'■ • rni thrnughnul each experiment; the numbers do not, thcrcfon' maik ab?cilute amount* of 

 prrwure; the rUe or /all is, of course, an absolute quantity. 



