885 
Physiology. — “Hvagqgeration of Deep Reflexes.’ By Prof. J. K. A. 
WERTHEIM SALOMONSON. 
(Communicated in the meeting of November 28, 1914). 
The graphic method of recording pathologically exaggerated deep 
reflexes sometimes offers interesting results. 
In the literature we find mentioned that exaggeration may show 
itself in different ways. A very slight tap on the tendon pro- 
duces an unusually brisk contraction: the threshold-value of the 
stimulus is lowered. But we also read that the lateney is shortened, 
that the duration, velocity and height of the contraction are increased; 
that a simple jerk may be changed into a tonic or clonic contraction. 
But even with this knowledge we are not quite prepared for the 
multiformity of the curves which may be recorded. 
I have tried to record the shortening, or more generaily the 
thickening of a muscle, following a tap on its tendon. Of course I 
found more or less of the changes mentioned before. But the curves 
seemed to be so absolutely different that I could not be content 
with the simple statement, that some patients showed one form of 
curve, some other patients quite another curve. We should like to 
know at least something about the mechanism of these different 
forms. 
A priori the idea of a change in the form caused simply by 
exaggeration of a reflex is rather difficnlt to conceive. We can 
readily understand that the reflex irritability is increased when an 
extremely slight tap on the tensor produces a very strong contract- 
ion. And this is conformed by clinical examination. But it is now 
generally understood, — and I think I too have contributed to this 
opinion -— that the deep reflexes must be considered from a physio- 
logical point of view as simple contractions, preceded by one 
double-phased current of action. As physiological variations in simple 
muscle-twitches we only know slight changes in height, duration 
and slope of the curves, caused by fatigue, by temperature ete., if 
we abstract from the changes caused by direct poisoning. But we 
do not know of an increased shortening, of a notable change in the 
latency or of a highly increased duration as long as we consider 
only simple muscle-twitches. 
If the simple muscle-twitch of the quadriceps known as knee jerk 
be recorded, we find under physiological conditions that the duration 
of the twitch is very nearly 0.20 second. 
