Physiology. — “The Myoclonic Reflexes’. By L. J. J. Muskens. 
(Communicated by Prof. H. ZwaarDEMAKER). 
(Communicated at the meeting of December 23, 1921). 
Under the influence of intoxication (camphorum monobromatum, 
essence of absinth) the myoclonic reflexes may be seen to shorten 
their normal long refractory stage to a small interval. For the rest 
the tracing presents the type of the patellar reflex, a rather steep 
beginning with a protracted termination. 
The myoclonic reflexes vary in some respect with the stimulus 
that elicits them. 
Those provoked by tactile- and acoustic-stimuli have a latent 
period, which is comparatively short; my measurements of this 
non-reduced reflex-time were 20—60 0. It appeared that for the 
tactile reflexes no important changes in the latent period were brought 
about neither by camphorum monobromatum intoxication (with 
extension of the reflex-movement over the whole animal), nor by 
ether-narcosis, nor by removal of a hemisphere. 
While with most reflexes a slight decrease of the reflex-time is 
noticeable with stronger stimuli, I found in three experiments with 
cats, specially carried out for this purpose, (in a definite latitude of 
intensity), a longer latency with a strong acoustic stimulus than 
with a weak one. 
Latency after acoustic stimulus in '/s9 sec. 
Cat. NO. Light blow | Moderate blow Heavy blow 
205 16: | De As 
178 Ben 129: | 2.16, “enka. dal 
The acoustic reflexes differ from the tactile reflexes also in other 
respects. In ether-narcosis a lengthening of the latency of the acoustic 
reflexes is observed; while the acoustic reflex disappears sooner in 
the narcosis than the tactile reflexes and also returns later. The 
latency of the myoclonic reflexes in other animals presents only few 
divergencies from the values found in cats and monkeys. Tactile 
stimuli administered to pigeons at the wing gave 2.5 and 3.5 fiftieths 
of seconds. For ink-fishes (Octopus) [ found, after adding some 
camphorum monobromatum to the seawater, similar latencies; in 
reptiles in a normal condition four fiftieths (Trepidonotus natrix). 
Just as everywhere in the study of reflexes we find in the myoclonic 
