vii THE MEDULLA OBLONGATA 417 



express pain, and are perfectly similar to those which the intact 

 rabbit makes when sharply stimulated. 



These sensory phenomena observed in animals after removal of 

 their fore- and mid-brains are analogous to those observed in man 

 during chloroform narcosis. Chloroform probably abolishes the 

 excitability of the cerebral hemispheres before it acts upon the 

 lower centres of the brain ; incompletely chloroformed subjects 

 often utter distressing cries, contort the face as if suffering pain, 

 and writhe under the surgeon's knife in a way that convinces 

 every one present that these are no mere reflex acts, but a true 

 expression of pain, although on waking they declare that they 

 have felt nothing. "Notre conviction profonde" (adds Longet) 

 " est qu'il y a eu sensation de douleur, et que son souvenir seul a fait 

 defaut. . . . Dans 1'e* tat de derni-sommeil, que d'idees aussi traversent 

 notre cerveau et qui, 1'instant d'apres, nous echappent ! " 



This theory of " bulbo-pontine consciousness had and still has 

 many opponents who would localise all psychical functions ex- 

 clusively to the cortex of the cerebral hemispheres, and treat 

 the phenomena described by Joh. Miiller, Longet, and Vulpian as 

 being purely unconscious reflexes. The obstacles to a clear and 

 incontestable solution by experiment are enormous and perhaps 

 insuperable. 



In our opinion more value, as evidence for a sensorium in the 

 spinal bulb, attaches to the observations on lower vertebrates (frog, 

 toads, tortoises) described above. When, e.g., the tortoise thrown 

 on its back makes all the associated movements of the normal 

 animal with head and limbs in order to resume its habitual 

 position, it is natural to ask what can be the nature of the strong 

 external stimuli which are able reflexly to discharge the entire 

 complex of simultaneous and successive muscular actions which 

 the animal performs with singular dexterity, after remaining for 

 some time motionless with its head and limbs withdrawn into the 

 carapace. It seems to us clear that in this case we are in the 

 presence not of externally evoked reflex actions, but of central 

 instinctive actions (i.e. such as are acquired by habit and trans- 

 mitted by heredity) which cannot fail to be accompanied by a 

 certain degree of consciousness, 



BIBLIOGRAPHY 



Structure of Medulla Oblongata : see recent text -books of Histology of the 

 Nervous System, including those of EDINGER, v. GEHUCHTEN, BECHTEREW, and 

 the standard text-books of anatomy. 



Physiology of the Cranial Nerves : a full bibliography will be found in the 

 classical text-books of Joh. MULLER, LONGET, and HERMANN (vol. ii., Special 

 Nerve-Physiology, by Prof. S. Meyer). 



Among the most important Monographs are : 

 BELL, CH. An Exposition of the Natural System of Nerves, 1824. 

 PANIZZA, B. Ricerche sperimentali sopra i nervi, ecc. Pa via, 1834. 



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