
-1905.] On Reciprocal Innervation of Antagonistic Muscles. 293 
Tetanus toxin likewise converts the cortical flexion into extension. The 
effect is in its case the more marked because, if the cortical examination be 
conducted in an early stage of the progressive malady ensuing on inoculation 
by a moderate dose, or conducted where the dose has been quite small, the 
tetanus is “local,” and confined to the limb the site of inoculation, and then, 
if the tetanus be “local” in one hind limb, eg., the left, the appropriate area 
of the right hemisphere yields knee-extension, whereas the corresponding 
of the left hemisphere yields knee-flexion. 
But these effects are better studied in the monkey. There, in my 
experience, to obtain primary extension of the crossed knee from the cortex 
is, as in the cat, extremely unusual. A number of experiments can be made 
without obtaining it at all. Even as a secondary movement it is extremely 
poorly represented in the cortex. For twenty instances of flexion at knee, it 
is, In my experience, often difficult to find one of extension at that joint. 
But, after tetanus toxin or strychnine, the whole “leg-area” of the cortex 
from all points of its surface will yield nothing but leg-extension, in which 
extension of knee is prominent, as an evident part of a primary combined 
movement. This is especially striking when the tetanus is still merely 
“local,” and confined to one hind limb, e.g., left. The “leg-area” of the 
right cortex then yields knee-extension everywhere ; the “ leg-area” of the 
left cortex yields the normal flexion results. The “leg-area” of the right 
cortex provokes moreover from many of its points extension of right knee 
.and ankle, as well as of left, though less strongly. The “leg-area” of 
left hemisphere does this little, if at all. Under moderate faradisation, 
the “leg-area” in the monkey, in my experience, moves the homonymous 
hind limb, in addition to the crossed, very slightly, and rarely normally, 
much less so than in the cat, though in both the movement is the same, 
namely, “extension.” So localised may be the toxic influence in its early 
stage that reversal of its cortical effect at knee may obtain while in the same 
hemisphere that on hip and ankle still remain flexion as usual. 
Similarly with the “arm-area.” In the cat, it is in my experience quite 
infrequent to obtain primary extension of the crossed elbow from the cortex. 
Flexion is readily and regularly obtained. Strychnine changes this: the very 
surface that yielded flexion then provokes extension, and strongly. But the 
dose of strychnine has to be larger than for conversion of the spinal reflex, 
and the conversion shows the phases before mentioned in regard to the knee- 
inhibition and its conversion in the case of the hamstring nerve. In the 
monkey, in my experience, the effect of strychnine and of tetanus toxin when 
pushed to the general convulsive stage, is often contrary to the effect in that 
stage In so many other animals. I have, namely, seen them produce, not 
