420 ELECTRIC PULSATION IN DESMODIUM GYRANS. 
inspection will show that the descending part of the mechanical 
record which corresponds to the downward movement of the leaf 
is steeper than the ascending part of the curve corresponding to 
the upward movement of the leaf. But in a contracted curve 
these characteristics are not very evident. I therefore took a 
mechanical record on a fast-moving drum. This is reproduced 
in fig. 11. Here the ascending part of the curve represents the 
motion of the leaflet downwards. The leaflet, on commencing to 
move, soon attains an approximately uniform velocity. It will 
be seen from the curve that it travels a distance of 6:25 milli- 
metres in 375 seconds, the velocity being 10 millimetres per minute. 
But during the ascent of the leaflet the velocity is very much 
reduced, when the velocity becomes approximately uniform. 
The leaflet only travels a distance of 6°25 millimetres in 
86 seconds, or a velocity of 4°3 millimetres per minute. 
The greater amplitude of the principal wave of electric 
response, which is the concomitant of the downward movement 
of the leaflet, is thus proved to be due to the greater velocity 
of motion of the leaflet during its period of descent. 
