889 
second contraction especially as contractions of this kind are some-- 
times found in completely paralysed patients. In some cases of 
myelitis or tumor of the spinal cord with complete paralysis we may 
often see involuntary movements in the paralysed limb. These move- 
ments set in after a slight peripheral stimulus, such as a simple 
touch, or the influence of the lower temperature of the air, or even 
without appreciable cause ; they cannot be prevented or modified by 
the patient. They may be considered as a spinal automatism. Generally 
they appear in the form of an adduction or a flexion of the lower 
limbs, more rarely as an extension movement. But a tap in the 
neighbourhood of the knee often produces a stretching movement 
of the leg. 
In some records it is not easy to distinguish between a clonus 
strietiori sensu and an automatism. The oserllations in the curve of 
fig.6 are rather slow for a true clonus, the rhythm being not quite 
5 per second. For an automatism the rhythm is rather fast. Perhaps 
we might consider it as an intermediate form: clonus and auto- 
matism are sufficiently closely related to render this admissible. 
There is still a third possible genesis for the after-contraction. In 
a former communication on “shortening reflexes” I pointed out, that 
these are always accompanied by a tonus-reflex, by which the muscle 
adapts itself to its new condition. As soon as a movement is necessary 
the muscle tonus is automatically regulated so as to put the muscle 
in the best condition for doing its work. Therefore we may a priori 
expect a tonus-reflex at the same time as the deep reflex. As a 
matter of faet we find that in records of simple deep reflexes, the 
simple twitch is generally followed by a slight elevation of the curve, 
indicating that immediately after the real muscle twitch tonus is 
increased for somewhat less ihan a second. The beginning of the 
tonus reflex is not sharply defined, as it starts before the end of the 
simple twitch. In favourable circumstances this after-contraction 
59 
Proceedings Royal Acad. Amsterdam. Vol. XVII. 
