i6o 
THOMPSON YATES LABORATORIES REPORT 
Excitation of either pinna evokes bilateral extension of wrists and elbows, the movement of the 
same side limb coming earlier and being stronger than that of opposite. 
Cat : — Cord cut above Ilnd cervical root. 
Excitation near xiphoid cartilage evokes bilateral extension of hips and ankles, more forcible and 
earlier in appearance on the side excited than on the crossed. 
Cat : — Cord cut above Ilnd cervical root. 
Excitation of skin of perineum provokes, besides movement of tail, an alternating progression 
movement of both hind-limbs, flexion of right hip alternating with extension of it, and coinciding in 
time with extension of left. Instead of this alternate movement of the hind-limbs, a synchronous bilateral 
extension of both hips and ankles, preceded by slight flexion of knees and similar to that got from 
abdomen, is not uncommon. 
Dipping fore-paw into warm water causes extension of wrist, flexion of elbow, then slight flexion of 
knee, and finally extension of hip and ankle. 
Dipping hind-paw causes slight flexion at knee, preceding forcible extension of hip. 
Dipping end of tail causes wagging of it. 
The above are reactions of frequent occurrence. The direction of their spread is not in 
accordance with PpLiiGER's law,* but is aboral. Thus, excitation started at fore-foot spreads to 
hind-foot and tail, but not upwards to neck ; excitation started in neck and pinna spreads to fore- 
limb, hind-limb, and tail ; started in hind-limb, spreads to tail, but not to fore-limb or neck. This 
is true for Cat, Dog, and Monkey. The greater facility of spinal conduction in descending than 
ascending direction is regular and overwhelming in experiments carried out in the above- 
mentioned way, but yet a certain amount of long, upward spread is observable. Excitation of 
hind-pad in Cat occasionally evokes, besides movement in its own and opposite hind-limb, a feeble 
movement in the fore-limb of the same side ; this movement is, in my experience, always 
extension of wrist and elbow with slight retraction of shoulder. The same spread occasionally 
occurs on increasing excitation applied to Vlth post-thoracic afferent root. Spread upwards is to 
the limb of the same side, never in my experience of spinal reflexes is it to the crossed fore-limb 
and not to the same side fore-limb, and never to either fore-limb without crossing to the opposite 
hind-limb. LucHsiNGER'st long diagonal spinal reflex between the limbs (in the Newt) I have 
never met in my experiments with Cat and Monkey. It is noteworthy that extension of elbow 
and knee, as uncrossed reflexes, are commoner by long spinal arcs than for short. 
The fourth of Pfluger'sJ classical laws of spinal reflexion states that, with associated 
spinal reflex centres, spread is always easier from lower to higher, i.e., from more aboral to less 
aboral centres, than vice versa. H. MuNK§ has expressed the opinion that impulses for touch 
irradiate easier in a direction from hind-limb to fore-limb. My own experience is consentient in 
traversing this fourth law of Pfluger. It is well, therefore, while recording the fact, to note that 
after high transection of the cord, reflexes from the fore-limbs are usually not on the whole so 
freely evoked as from the hind-limbs and tail. It has often seemed that the motor neurons high 
up, and therefore nearer the transection, are less receptive of impulses, and are partially blocked or 
under ' shock,' especially for impulses arriving at them from sources outside their own local region. 
* Uber die sensorische Functionen des 
Riickenmarkes,' Berlin, 1853. 
t Pfliiger's ' Archiv,' vol. 22, p. 179, 1880. 
I Loc. cit. 
§ ' Sitzungsberichte d. Kcin. Akad. der Wissench. 
z. Berlin,' 1893. 
