

1905.] On Reciprocal Innervation of Antagonistic Muscles. 168 
describing the “extensor thrust” of the limb, I drew attention to its 
significance for locomotion. “Spinal induction” obviously tends to connect 
this “extensor thrust” as an after-effect with precurrent flexion of the limb. 
In the stepping forward of the limb the flexion that raises the foot and 
carries it forward clear of the ground though temporarily checking the 
reflex discharge of the antagonistic arcs of extension is, as it continues, so 
to say, sensitising them to respond later in their turn by the supporting 
and propulsive extension of the limb necessary to progression. In reflex 
sequences an antecedent reflex would thus not only be the means of 
bringing about an ensuing stimulus for the next reflex,* but in such 
instances as the above, will predispose the arc of the next reflex to react to 
the stimulus that will arrive. 
In recentlyt attempting to deal with the factors that determine the 
succession of reflexes in time, I mentioned this factor, “spinal induction,” 
but laid less stress on its potency than its phenomena now seem to me 
really to warrant. 
* Loeb’s “ Ketten-reflexe,” discussed in his ‘ Vergleichende Gehirnphysiologie u. 
Vergleichende Psychologie,’ Leipzig, 1899, p. 96, and seg. ; compare also Exner, ‘ Entwurf 
einer physiologischen Erklarung psychischer Erscheinungen,’ Vienna, 1894, p. 102, and 
seq., under “Successive Bewegungscombinationen ” ; also Wundt, ‘Grundziige der physio- 
logischen Psychologie,’ vol. 1, p. 181. 
+ Brit. Assoc., Cambridge, 1904. Address to Section I. 
