Studies on the flexor reflex.-V. General conclusions

The experiments described in the preceding four papers bear on various problems presented by reflex activity. Their results confirm some of the inferences already drawn elsewhere from other experimental work, and they allow certain further inferences. A brief prefatory statement of all these inferences and of the experimental evidence which allows them will advantageously introduce the description of the processes set up in the ipselateral flexor centres of the spinal cord by a single centripetal volley and by a single antidromic volley. Then, finally, discussion of the theories of reflex excitation can be undertaken in the light of the present experimental observations. the statement treats of the subject in its present phase only; the references to relevant papers are therefore restricted in the main to the more recent ones. II. Inferences from Experimental Observations. 1.The convergence of Different Afferent Paths on the same Motoneurones The following evidence shows that this occurs:- (a)Histological .-Each motoneurone receives its “boutons terminaux ” from many individual afferent terminals (Cajal, 1903). (b)Physiological .-Centripetal volleys set up indifferent afferent nerves excite the same motoneurones (Camis, 1909; Cooper, Denny-Brown, and Sherrington, 1926; 1927; Sherrington, 1929; Cooper and Denny-Brown, 1929 ; Eccles and Sherrington, 1930 ; 1931,a ; 1931,b ).