EEFLEX ACTION OF THE SPINAL COED. 301 



understood, had been mentioned more or less definitely. In 

 the history of important advances in physiological knowl- 

 edge, it has often been the case that discoveries have been 

 foreshadowed by the earlier writers ; and bibliographical re- 

 search shows that the literature of the cord as a nerve-centre 

 forms no exception to this, which is almost the rule. Some 

 of the allusions to the cord as a centre of reflex action, 

 made anterior to 1833, are vague and indefinite'; but, on 

 the other hand, certain excito-motor actions were very ac- 

 curately described, as early as 1812. Marshall Hall grouped 

 and classified these phenomena, and showed their relations 

 to the cord as an independent centre ; but, as we shall see, 

 he has no claim to the title of the discoverer of reflex action, 

 and his experiments presented little that was really new. 



AVhytt, in his work on the " Vital and other Involuntary 

 Motions," states that the involuntary and mixed motions 

 proceed from a stimulus, the latter being partly, and the 

 former not at all, under the power of the will ; 1 and, by a 

 stimulus, he means an impression made upon the sensory 

 nerves. 



Prochaska, who wrote between 1778 and 179 7, states that 

 the sensorium commune extends to the medulla spinalis, and 

 that this " is manifest from the motions exhibited by decapi- 

 tated animals, which cannot take place without the consen- 

 tience and intervention of the nerves arising from the me- 

 dulla spinalis ; for the decapitated frog, if pricked, not only 

 withdraws the punctured part, but also creeps and leaps, 

 which cannot be done without the consensus of the sensorial 

 and motor nerves, the seat of which consensus must neces- 

 sarily be in the medulla spinalis the remaining portion of 

 the sensorium commune." a He calls this " reflexion," and 

 speaks of it as taking place without consciousness, describing 

 many phenomena now familiarly known as reflex. 



1 WHYTT, Works, Edinburgh, 1768, p. 170. 



8 PROCHASKA, A Dissertation on the Functions of the Nervous System, Syden- 

 ham Society, London, 1851, p. 430. 



