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of the leg during the clonus. This difficulty was overcome by 
attaching a clamp to the upper part of the tibia and another to 
both malleoli, and connecting them by a very light hollow rod. To 
this rod the tambours were screwed with a pair of collars. With 
this arrangement which proved to be entirely satisfactory, I was 
able to record the thickening curve of any desired muscle of the 
leg and also the displacement of the foot with respect to the leg. 
Fig. 1. 
Shortening reflex in the tibialis anticus of a healthy 
man. 
Upper curve: displacement of the foot. 
Middle curve: thickening curve of tibialis anticus. 
Lower curve: time marks of 0.1 second. 
I reproduce a few records (fig. 1 and fig. 2) which were taken 
in this way. The upper line shows the movement of the foot ; rising 
of the curve indicates dorsal flexion. The middle curve is a record 
of the thickening of the tibialis anticus. The time curve gives marks 
of 0,1 of a second. 
Fig. 1 shows the tibialis contraction occurring with a short dorsal 
flexion of the foot. Fig. 2 gives the record of tibialis contraction 
caused by a rapid dorsal flexion of the foot, the foot being kept in 
dorsal flexion for nearly two seconds. In this last record we clearly 
see the initial tibialis twitch followed by the reflextonus-thickening. 
From the records we soon gather the fact, that the tibialis re- 
sponse immediately follows the foot movement. By comparing a great 
many records we also find that the interval between the commence- 
ment of the foot-movement and the beginning of the tibialis-muscle- 
twitch is of a very short and yet extremely constant duration. If as 
