282 ORIGINAL ARTICLES AND CLINICAL CASES 



contrary to the accepted view of its function. In current text-books of 

 physiology and psychology it is frequently stated that the motor area is 

 the (sole) efferent path of voluntary movements from the cortex. Even 

 investigators like Rothmann, who have studied recovery from hemiplegia 

 in animals, look upon the stimulable area as the chief source of the 

 efferent fibres concerned with habitual activity. In speaking of con- 

 duction through extrapyramidal paths Rothmann says, " Diese extra- 

 pyramidal Leitung diirfte fiir die Erlernung neuer Bewegungen von 

 grosster Bedeutung sein, wahrend die in festen Besitz des Individuums, 

 iibergegangenen gut eingelernten Bewegungen vorwiegend die direkte 

 Verbindung von Grrosshirnrinde una Riickenmark, also die cortico- 

 spinale Bahn, benutzen werden " [16], Von Bechterew advances a 

 similar view in describing the course of conditioned-reflex arcs across 

 the cortex from the sensory projection areas to the motor area [1]. 



If this conception is correct for higher forms, it means that a pro- 

 nounced change in the function of the stimulable cortex has occurred 

 somewhere above the rodents in the evolutionary scale. But such 

 changes in function are rare and in this case the evidence does not 

 seem to show more than that the stimulable cortex of higher forms 

 has taken over a part of the function which the caudate nucleus 

 exercises in rodents. 



King [8] , using the Marchi method, concluded that the pyramidal 

 tract in the rat is small and unimportant, but Ranson [15] has shown 

 that it is quite large, though made up chiefly of thinly medullated 

 fibres. The area of the tract shown on Ranson's figures is propor- 

 tionally greater than in primates, so that it cannot be argued that there 

 is any great increase in the anatomical importance of the tract with 

 ascent in the evolutionary scale. 



The physiological evidence does not seem sufficient to prove that 

 the pyamidal tracts, even of primates, are the efferent path for 

 impulses to voluntary movement. Fritsch and Hitzig [5] pointed out 

 that the paralysis following destruction of the stimulable area is only 

 partial. Writing of the motor centre they stated that " . . . es ist 

 sicher, dass eine Verletzung dieses Centrum die willkiirliche Bewegung 

 des von ihm sicher in einem gewissen Abhangigkeit stehenden Gliedes 

 nur alterirt, nicht aufhebt, dass, also irgend einem motorischen Impulse 

 noch andere Statten und Bahnen offen stehen um geboren zu werden 

 und um zu den Muskeln jenes Beines zu eilen . . ." Nothnagel ob- 

 served recovery from the effects of unilateral injury to the motor area 

 and Carville and Uuret [4] first showed that the recovery is not due to 



