296 Prof. C. S. Sherrington. [Apr. 17, 
hind leg, even before the “local” tetanus has obviously invaded the fellow 
limb of the opposite side, a slightly clenched jaw and an immobile pursing of 
the lips has several times given warning that general tetanus had really set 
in, long before any trace of general convulsive seizures or any involvement of 
the arms was detected. Tetanus toxin has also certainly intensified the 
reactions of the cortical areas that give retraction of the neck and retraction 
of the abdominal wall. | 
The progress of the change wrought by these agents in converting these 
reactions of the cortex from their usual form to the diametrically opposite 
seems to involve the same kind of steps as that noted above in their con- 
version of the inhibitory hamstring nerve effect on the knee extensor. There 
stages can be found in which the inhibitory effect is less than normal, yet is 
not replaced by excitatory. So with the cortical opening of jaw, in early 
tetanus a grade is discoverable when faradisation of the cortex produces a 
slight opening of the jaw—a mere “loosening” of the Jaws so to say—dis- 
tinctly less than normal and hardly effectively opening the mouth. Also 
with the “leg-area” of the cortex, at an early stage of the tetanus it would 
seem that an undue but far from exclusive preponderance of plantar extension 
at ankle over dorsal flexion at that joint exists, while the symptomatic knee- 
extension is as yet not excitable though knee-fiexion is almost in abeyance. 
Neither under tetanus toxin or strychnine have I at present observed 
conversion of the abducens inhibition* into excitation. 
In this brief account it might appear that the effects of tetanus toxin and 
of strychnine on the cortical reactions seem identical. In reality a number 
of differences between them appear to exist. These and other points I must 
reserve for a more detailed communication. But the foregoing observations 
appear to give an insight into at least a part of the essential nature of the 
condition brought about by tetanus and by strychnine poisoning. These dis- 
orders work havoc with the co-ordinating mechanisms of the central nervous 
system, because in regard to certain great groups of musculature they change 
the reciprocal inhibitions, normally assured by the central nervous mechanisms, 
into excitations. The sufferer is subjected to a disorder of co-ordination which, 
though not necessarily of itself accompanied by physical pain, must inflict 
on the mind, which still remains clear, a torture inexpressibly distressing. 
Each attempt to execute certain muscular acts of vital importance, such as 
the taking of food, is defeated because from the attempt results an act 
exactly the opposite to that intended. The endeavour to open the jaw to take 
food or drink induces closure of the jaw, because the normal inhibition of the 
stronger set of muscles—the closing muscles—is by the agent converted into 
* Sherrington, ‘ Roy. Soe. Proc.,’ vol. 52, 1893. 
