574 PHYSIOLOGY CHAP. 



The afferent paths from the cortex to the cardio-motor bulbo- 

 spinal centres by which changes in the frequency and intensity of 

 the cardiac rhythm are produced, are normally excited reflexly by 

 emotions, by excessive work, by the tension of the muscles, and by 

 variation in respiration. But there may exceptionally be percept- 

 ible acceleration or diminution of the cardiac rhythm associated 

 with a simple, direct voluntary impulse, without obvious change in 

 the respiratory rhythm (Tarchanoff, Patrizi) (Fig. 293). 



From the effect of the emotions on the secretions and specially 

 on salivation and perspiration, on the muscle cells innervated by 

 the sympathetic, on the skin, the alimentary tract, and the 

 urinary system, it is highly probable that artificial stimulation 

 of the cortex also produces similar effects. In fact, Bochefontaine 

 first, and after him many other observers, found that faradisation 

 of the motor area in the dog produced a flow of saliva from the 

 salivary glands of both sides. Changes in sweat secretion were 

 not observed. In experimental epilepsy Francois -Franck and 

 Pitres found, both in the goat's foot and the dog's, that drops of 

 sweat were exuded during the convulsions, and Adamkiewicz, 

 in cases of partial epilepsy in man, noted abundant perspiration 

 in the skin of the limb that was convulsed. 



The observations of Bochefontaine and others on gastric, 

 biliary, and urinary secretions gave no definite results. But 

 Bochefontaine, Francois - Franck and Pitres, Bechterew and 

 Mislawsky, and Sherrington, obtained more positive vesical re- 

 actions on exciting different points of the motor area. According 

 to von Pfungen (1906), the movements of the gut can also be 

 influenced by cortical stimulation. 



VIII. Intimately connected with the study of the motor 

 effects obtained on cortical faradisation, are the epileptiform 

 convulsive phenomena which are often produced when the currents 

 employed are unduly strong or applied for too long a time, or 

 when the cerebral cortex is abnormally excitable. Hitzig and 

 Fritsch, who discovered the excitability of the cortex, first pointed 

 out this fact, and recognised that the epileptic attacks began 

 with convulsions of the muscles corresponding to the centre first 

 excited, and afterwards spread to other muscular groups. Shortly 

 before their discovery, however, Hughlings Jackson had concluded 

 from the clinical study of epileptiform convulsions localised to 

 certain groups of muscles that certain forms of epilepsy depend 

 on lesions of cortical centres which produce periodical discharges 

 (discharging lesions) in the direction of the corpus striatum. The 

 observations of Hitzig and Fritsch and of Ferrier (1874) may be 

 taken as experimental confirmation of Jackson's theory. 



The epileptic convulsions obtained on cortical faradisation 

 differ from simple motor reactions because they persist and 

 sometimes increase after the stimulus has ceased, and because of 



