
1905.] On Recwprocal Innervation of Antagonistic Muscles, 295 
the same effect; or as was shown by Woodworth and myself,* stimulation of 
even distant afferent nerves, ¢.g., plantar or saphenous. Here the action of 
the powerful closing muscles is reflexly inhibited while the weaker opening 
muscles are reflexly excited—it is, in fact, a case of Astacus claw, except that 
the inhibition is central, not peripheral. This reflex “opening” is in the 
decerebrate animal converted into reflex closure by tetanus toxin and by 
strychnine, the inhibition of the predominantly powerful closing muscles 
being converted into excitation of them. 
Similarly, when the “face-area” of the monkey’s cortex is tested by 
faradisation after exhibition of strychnine, the points of surface that, prior to 
the drug, yielded regularly the free opening of the jaw, yield strong closure 
of the jaw instead. Now closure of the jaw, is in my experience, quite 
an infrequent movement to obtain from the cortex of the cat or monkey,f 
one frequently fails to elicit it by moderate stimulation from any point 
whatsoever. When it does present itself, it tends to be unreliable even at the 
point at which it may have been evoked. On the other hand, opening of the 
jaw is always readily and regularly elicitable from a large field of the 
“face-area.” And adjoining and overlapping this large area whence steady 
opening of the jaw is obtained, is an area whence, as Ferrierf first pointed out, 
“rhythmic alternating opening and closing of the jaws,” as in feeding, can be 
evoked. Under tetanus toxin or strychnine the whole of this combined area 
not only ceases to yield opening of the jaws, either maintained or rhythmic, 
but yields closing of them instead—often with visible retraction of the tongue. 
For this conversion larger doses of strychnine have, in my hands, been required 
than for conversion of knee-flexion into extension. With tetanus toxin the 
conversion appears the more striking when examined early in the progress of 
the intoxication, because it may be found at a stage precedent altogether to 
the occurrence of any general convulsions, and also because it can then 
sometimes be found to be unilateral, that is, to be present in the “ face-area ” 
of one hemisphere§ without, or almost without, any affection of the “face-area” 
of the other hemisphere. The reactions of the normal field thus remain 
for comparison in the same individual with the reactions of the abnormal 
field. 
The tetanus toxin in my experiments in the monkey has shown marked 
predilection for the closure mechanism of the jaw. After inoculation in the 
* Journal of Physiology,’ vol. 28, 1904. | 
+ The species of monkeys used have been I. rhesus, callothrix, and cynomolgus. No 
reference is here meant to the anthropoid apes. 
{ ‘Functions of the Brain,’ 1876. 
§ The hemisphere, the reactions of the “face-area” of which are earlier affected, is in 
the case of inoculation in a limb the hemisphere contralateral to the limb inoculated. 
