40 
THOMPSON YATES LABORATORIES REPORT 
Thus : — By excitation of the sole, flexion of hallux can be elicited more readily than protrusion 
of anus ; from skin of perineum, conversely, protrusion of anus more readily than flexion of hallux, and 
this with prefixed plexus. 
From Ilird, IVth, Vth, and Vlth cervical afferent roots, action of supinator longus is usually more 
facile than action of triceps ; from Vllth cervical there is not so great a preponderance of one or other ; 
from Vlllth cervical and the four highest thoracic roots, action of triceps is the more easily obtained as a 
rule. 
In the Cat, active flexion of the knee is usually a more facile reflex than active flexion of hip in 
response to excitation of IXth, Vlllth, and Vllth post-thoracic afferent roots ; but Ilnd, Ilird, IVth, 
Vth, and Vlth roots as readily yield flexion of hip as of knee, as a rule. 
In MacMus, flexion of thumb and fingers is more readily obtained by excitation of the skin of the 
hand itself than of any other part of the limb ; the Vllth and Vlllth cervical afi"erent roots and the 1st 
thoracic are those supplying the skin of the hand, and the motor root of each of these segments innervates 
the flexor muscles of the digits. A similar arrangement obtains between planta and hallux. 
In the Cat, mechanical or thermal stimuli applied to the pad evoke primarily and most easily reflex 
flexion of the toes ; this is true in fore-foot and in hind-foot. 
In the Cat, either dorsal flexion or plantar flexion of ankle may be the reply to cutaneous stimuli 
on the foot, but dorso-flexion is the more usual, and is more certainly obtained from the dorsum pedis than 
from the sole, and least certainly obtained from the 4th toe. Now, the dorsum is supplied by sensory 
roots anterior to those supplying the sole, and especially to those supplying the 4th toe ; i.e., to the sole 
and to the 4th toe the IXth post-thoracic root sometimes, and the Vlllth always, contributes ; to the 
dorsum, the Vlllth slightly, the IXth never, contributes ; while the Vlth contributes to the dorsum, but 
never to the sole and 4th toe, the Vllth being common to all. Now, dorsal flexors of ankle derive nerve- 
fibres from the Vlth and Vllth roots chiefly, the plantar flexors from the Vlllth and Vllth chiefly. 
In the Cat (and Monkey), reflex extension of hip is more readily obtained from the afi^erent roots 
posterior to the Vlth (in Monkey Vth) than from the roots in front of Vllth (in Monkey Vlth). The 
extensors of the hip receive their motor innervation chiefly from roots behind Vlth (and Vth, Monkey). 
Excitation of the outer side or edge of the sole evokes (both in Cat and Monkey), besides dorso- 
flexion at ankle, some tilting upward of that edge of the foot. This outward tilting is not elicited from 
the inner edge of the foot, inward tilting being then not unusual. Now, in the Cat, the outer edge of 
sole is supplied by Vllth -J- Vlllth ganglia (post-thoracic), while inner edge by Vlth + Vllth; but outer 
edge is more richly supplied by Vllth than is inner edge. Now, peronei get motor neurons from Vllth 
and Vlllth motor roots, so that peroneal contraction might be expected to be stronger from outer edge 
than inner on the rule of segmental proximity. Same holds in Monkey on substituting roots V, VI, and 
VII for the above. 
Dorso-flexion of ankle in Monkey is less easily obtained as a spinal reflex than flexion of the other 
hind-limb joints; the roots whence it is best obtained are the Vllth and the Vlth. These are the sensory 
roots of the very segments which supply motor fibres to the pretibial and peroneal muscles. 
The cremasteric reflex obtainable by scratching inner side of thigh and groin is obtained thus when, 
in Monkey, all the posterior roots of the region except Ilnd and Ilird lumbar have been severed. It is 
also obtained by direct excitation of IlIrd lumbar root. 
Extension of the hip and flexion of the knee can be with less difficulty provoked from the part of the 
outer aspect of the thigh behind my mid-dorsal line of the limb than from the region in front of it. As 
a futher example may serve Cayrade's* observation that after mid-thoracic transection in the guinea-pig, 
pinching the root of tail causes flexion of the knee ; stroking the belly adduction of hip and extension at 
knee. 
This rule offers, I believe, especially when stimuli not far removed from minimal are 
employed, a useful key — as regards short paths — to many topographical relationships between 
field of excitation and field of reflex movement. Its existence is notable in face of the oblique 
correlation which was shown in my previous experiments,t to obtain over a large part of the trunk 
* ' Les Mouvements Reflexes,' Thesis, Paris, 1864. 
t 'Phil. Trans.,' B, vol. 184, p. 754. 
