570 PHYSIOLOGY CHAP. 



Similar effects to those obtained by the direct stimulation of 

 the cortex result both from stimulation of the nerve fibres of the 

 corona radiata, after removal of the grey matter, and from reflex 

 stimulation, due to excitation of sensory nerves on their end- 



organs. 



These and other similar facts have led some authors to the 

 conclusion that on stimulation of the cortex there is always, along 

 with contraction of certain muscles, relaxation of their antagonists, 

 and that under normal conditions there is never synchronous con- 

 traction of antagonistic muscles. The later observations of E. du 

 Bois-Eeymond (1902) show plainly that the relaxation of certain 

 muscles during the contraction of their antagonists is not a general 

 specific law ; that there is a whole series of facts which are opposed 

 to this so-called " law," and generally speaking that the inhibitory 

 effects are not confined to the antagonist muscles, but may also 

 extend to other muscles of any function. While admitting the 

 accuracy of the inhibitory phenomena described by Sherrington 

 and others, there is no necessity for undue generalisation. 



VII. In addition to motor and inhibitory effects on the 

 voluntary muscles the stimulation of the excitable area of the 

 cortex produces effects, also motor or inhibitory, in the organs of 

 vegetative life. 



It is a matter of common observation that emotional states of 

 different kinds are associated with respiratory, circulatory, and 

 secretory changes. Since the discovery of Hitzig and Fritsch, 

 a number of experimenters have tried to localise the centres 

 of these special reactions in the cortex by the usual method 

 of faradic stimulation, but these attempts have not led to any 

 such precise localisation as in the case of the voluntary move- 

 ments. Generally speaking, it may be stated that the electrical 

 excitation of any point of the so-called motor area may excite 

 respiratory, cardiac, or secretory effects. But there is no 

 specific localisation for these reactions, only a diffuse localisation 

 which extends all over the area which is known to be excitable. 

 Beyond this zone cortical stimulation is ineffective, when moderate 

 currents incapable of provoking convulsive attacks are used. 



Electrical stimulation of the motor area in the dog produces 

 (Danilewsky, Bochefontaiue, Frangois-Franck, and Pitres) some- 

 times acceleration, sometimes retardation of the respiratory rhythm, 

 independently of the exact point of stimulation, and rather in 

 relation to the strength of the stimulus. Bechterew obtained 

 similar results, while others described special inspiratory and 

 expiratory effects on exciting fixed and definite points of the 

 motor zone. 



The differences noted by the various experimenters probably 

 depend on the degree of anaesthesia of the animal, perhaps also 

 on the nature of the anaesthetic. Under chloral, Eichet observed 



