40 THOMPSON YATES LABORATORIES REPORT 
value of sometliing over loo mm. of mercur)- (PI. II). By stimulating the skin mechanically 
or by temperature changes, or by faradising the central end of an afferent nerve, e.g. of the 
foot, reflex increase of blood pressure raising it 20 to 30 mm. of Hg is easily obtained. It is 
only in the first few hours immediately succeeding the initial trauma of transection that the cord, 
being ui a condition of shock, gives no reflex response by its vascular musculature any more than 
by its skeletal musculature. This visceral shock seems no more severe in the higher than in the 
lower vertebrata. It is as regards the performances of the skeletal musculature that great 
difference exists in regard to shock distinguishing between the spinal frog and spinal monkey. I 
have ventured to suggest that the spinal shock of the latter animal is connected with an isolation 
dystrophy such as occurs in cases where nerve-cells habitually actuated by other nerve-cells are 
suddenly and completely cut off from their influence. That the difference is very great and real 
between lower and higher types in this respect of spinal shock is shown by such instances as the 
following. The cat from which the Rolandic area of the cortex has been removed, so as to ablate 
the whole of the limb centres from one hemisphere, if some weeks later ' decerebrate rigidity ' be 
induced in its limbs, yields the rigidity without perceptible difference between the sides both right 
and left. But in the monkey similarly prepared, a great difference between the limbs of the two 
sides is apparent. The rigidity on the side crossed to the cerebral lesion is very much less than on 
the homonymous side. At the same time it must not be thought that the whole depression of 
function in the parts innervated behind the spinal transection is due to removal from them of merely 
cerebral influence. That that cannot be the case is shown by a fact that I have several times had 
opportunity to observe, namely, that the performance of a second spinal transection some weeks 
later, and some segments behind a former spinal transection, is followed by the recrudescence of 
many of the original symptoms of depression of function that had followed the original transection. 
It is significant that such a second transection behind a previous one causes a considerable increase 
in the descending spinal degeneration, showing that there descend from upper parts of the spinal 
cord many channels arising in tho-e upper spinal regions, and connecting them with other spinal 
regions further back. 
Whence comes the great difference existent between, on the one hand, ape and man, and, 
on the other, fish and frog, as regards the depression of the reactions of the skeletal musculature 
ensuent upon total transverse lesion of the spinal cord ? 
To refer briefly for a moment to initial shock due to spinal section in the monkey, there 
can liardly be witnessed a more striking phenomenon in the whole physiology of the nervous 
system. From the limp limbs, even if the knee-jerks be elicitable, no responsive movement, 
beyond perhaps a feeble tremulous adduction or bending of the thumb or hallux, can be evoked 
even by insults of a character severe in the extreme. That which the delicate yellow spot is to 
the sensifacient sheet of the retina, may the thumb and index be said to constitute in the great 
sensifacient field of the limb. Nevertheless a hot iron laid right across the thumb, index, and 
palm remains an absolutely impotent excitant, or able only to evoke a faint flexion of the thumb ; 
the crushing of a finger has no greater effect. A huge afferent nerve, such as the internal 
saphenous, containing some five thousand sensory nerve-fibres, when laid across the electrodes and 
