386 Proceedings of Royal Society of Edinburgh. [sess. 
quadriceps femoris, and left gastrocnemius ; (3) marked clonus of 
the left ankle and left knee-joints ; and (4) to a less extent impaired 
voluntary motor power of the right leg, with increased ankle and 
knee jerks and clonus. 
Knee Jerk . — The method of recording this, which I followed, 
was to connect two recording tambours, the first with a tube having 
a flexible extremity, which could he held over the patellar tendon, 
and through which the tendon could he tapped ; the second with a 
receiving tambour, the button of which was held in contact with the 
leg. The first recording tambour indicated on a rapidly revolving 
cylinder the instant at which the tendon was tapped, and the second 
the moment that the limb began to move. A chronograph, vibrating 
100 per second, enabled the interval between the tap and the move- 
ment to he ascertained. Care was taken that the tubes connected 
with the tambours were of the same length. 
In both limbs the time was found to he about ’06 second — a 
rather longer interval than that stated by most other observers to he 
the case at any rate in health (see Tracing I.). 
Ankle Jerk . — To ascertain this the flexible end of the tube con- 
nected with the first recording tambour was held in contact with 
the tendo-Achilles, whilst the button of the receiving tambour was 
held in contact with the ball of the great toe. In the case of both 
limbs the time which elapsed between the tap on the tendon and 
the resulting movement was about -08 second (see Tracing II.). 
Plantar Reflex . — This was ascertained in the right leg only ; the 
cutaneous sensibility of the left being so much impaired, that its 
plantar reflex was practically non-existent. The method followed 
was to substitute for the flexible end of the tube connected with the 
first recording tambour an ordinary receiving tambour, to the button 
of which was fixed a pin point. The button of the other receiving 
tambour was held in contact with the lower end of the thigh. The 
interval between the prick thus applied to the sole of the foot and 
the resulting movement was T6 second. 
Wrist Jerk . — To ascertain this the flexible end of the tube con- 
nected with the first recording tambour was laid on the tendon of 
the supinator longus of the left arm, and the button of the receiving 
tambour was held over the metacarpal region of the hand. The tap 
applied to the tendon through the tube readily produced the desired 
