PHYSIOLOGY OF THE POSTERIOR PITUITARY. 507 



attributes Vulpian passed an electrode through it, that part 

 in contact with the cortex being insulated. The underlying 

 white substance was thus alone stimulated. He found that 

 the latter was far more easily excited than the cortex. It 

 seems clear that in these experiments the increased excitability 

 was due to the closer proximity of the central brain. "All the 

 functions of the brain can persist," says Brown-Sequard, "after 

 the complete destruction of an entire lobe." 13 Experimental 

 and clinical evidence, however, only eliminate motility and co- 

 ordination from the hemispheres. The cortex, as regards cere- 

 bral localization, merely loses the "motor" attribute suggested 

 by the term "motor area," and is shown, by its functional 

 relations with the underlying structures, to be a vast sensitive 

 surface, to the "areas" of which the term "sensory" might be 

 more fittingly applied. 



The practical bearing of this may be illustrated by an 

 experiment that will recall some of the familiar features of 

 the earlier portions of this work and at the same time point 

 to the central brain as the source of motor phenomena. This 

 experiment, referred to by Professor Foster, is as follows: "It 

 has been observed that in certain stages of the influence of 

 morphine the cortex and the rest of the nervous system are 

 in such a condition that the application of even a momentary 

 stimulus to an area leads not to a simple movement, but to a 

 long-continued tonic contraction of the appropriate muscles." 

 This, we now know, is due to suprarenal overactivity induced 

 by the drug. Cerebral hyperaemia, we have seen, is the source 

 of the majority of phenomena that follow the ingestion of 

 drugs that are sufficiently active to stimulate the adrenals. 

 The intense headache of quinine and other agents is obviously 

 due to this congestion of the cerebral vessels; muscular con- 

 tractions, tetany, etc., are also familiar results of suprarenal 

 overactivity; indeed, digitalis, one of the most active supra- 

 renal stimulants, is particularly active in predisposing muscles 

 to contraction and in experimental animals suitably dosed a 

 minimal current without the drug will produce maximum effects 



"M. Duval: Loc. cit., p. 115. 



