EXAMINATION OF SOME SPINAL NERVES 157 
giving exactly an appearance of the limb struggling to get itself free. Freusberg's* 'beating- 
time' reflex (Dog), which can also be studied in the Cat, is another example. The 'tail-wagging' 
reflex, even in isolated tail cord, which I have seen also in the Monkey, is another. The flicking 
backwards and forwards of the ear in the Cat is another. I would distinguish carefully between 
these reflexes, with ' alternating discharge ' in antagonistic muscles, and the discharge which is 
merely clonic in character. 
It is true that the spinal ' march ' is much more restricted, both in time and place, in the 
Monkey than in other lower laboratory animals. This is an indication of the extent of the shock 
and of isolation-alteration, both greater in Monkey than in the other types. Yet in a Monkey, 
after a complete spinal transection in the Vlllth post-thoracic segment^ I have seen^ fourteen days after 
the transection^ alternating side to side movements of the tail evoked by excitation of the skin near the tip 
of the tail. I have never seen freer wagging of the tail, even when the cord was transected at 
high thoracic levels. The centre must have lain at the extreme apex of the cauda equina. 
No better example could be of the slightness of solidarity possessed by the isolated cord of the 
Monkey as a whole : the reactions obtainable from one local region are not notably increased 
or more facile when in addition to that spinal region a large part of the adjoining cord remains 
attached to it, than when it is isolated and remains by itself apart from all other regions of the 
cord. The individual regions of the Mammalian cord, e.g., the limb regions, seem to contain 
comparatively few parts in their mechanism which are intimately dependent on elements in other 
regions of the cord outside their own. 
It is noteworthy that in the Monkey it is usual for some movements, e.g., the flexion of 
elbow and flexion of knee, to be, although feeble and difficult to elicit, curiously prolonged and 
deliberate, the new position assumed by the limb only slowly being relinquished. This character 
is even better seen, and sometimes is developed to an extraordinary degree, when the transection, 
instead of being post-bulbar in position, is pre-pontine. 
The above examples served to show that the rule of segmental proximity operates potently 
in determining the starting place of the march, i.e., determines the locus of the initial and leading 
movement. Also, that in its progress the march of a spinal reflex, even along short paths, does 
not exclusively observe Pfluger's 4th law, but travels down as well as up the cord. Also, that 
of two movements evoked which, segmentally considered, are distant, and in the same direction 
from the starting point, the appearance of the more distant movement rarely precedes that of the 
less distant, provided the two be in the same lateral half of the body. The upward and down- 
ward spread suggests a relation to the intraspinal bifurcation of the afferent root-fibres discovered 
by Frithjof Nansen (i887),t and confirmed by Cajal (1889). J 
The nerve-cells for the extensors of the knee, rarely as they initiate, i.e., are primary, in 
any spinal reflex, are frequently involved in the latter progress of the march. Thus flexion of 
* Pfliiger's 'Archiv,' vol. g. 
t ' The Structure ami Combinations of the Nervous System of Amphioxus,' 'Bergen's Museum Arsbereting ' for 1886. 
Bergen, 1887. 
X ' Contribucion al Estudio de la Estructura de la Medula espinal,' 'Revista trimestral de Histologia normal y patologica.' 
March, 1889. 
