MULTIPLE AND AUTONOMOUS ELECTRICAL. RESPONSE 



then takes place more gradually and at a much slov/er rate. 

 This movement is due to natural recovery, aided by a 

 moderate excitatory contraction of the upper half of the 

 pulvinus. 1 give herewith a table showing the characteristic 

 rates of movement in the different phases of the entire 

 pulsation. 



TABLE SHOWING RATES OF MOVEMENT AT DIFFERENT STAGES OF 

 PULSATION IN DESMODIUM. 



Down-movement Up-movement 



Total period . . 45 seconds Total period . . 70 seconds 



Average rate . -61 mm. per second I Average rate . '4 mm. per second 



Maximum rate . "j ,, ,, ,, Maximum rate . *5 ,, ,, ,, 



Duration of pause . 40 seconds j Duration of pause . 35 seconds 



Several facts are brought out in this table which are of 

 special importance, and first we observe that the excitatory 

 impulse which causes the down-movement is brief and quickly 

 exhausted. This is seen by the great distance covered 

 during the first ten seconds, after which the movement 

 gradually slows down. This indicates a short-lived impulsive 

 action, the subsequent movement of the leaflet being mainly 

 due to inertia. There is then a pause in the down-position, after 

 which the up-movement commences. It will be noticed here 

 that this movement is more gradual and prolonged than the 

 down-movement. From the indications given by these 

 characteristic movements, we may conclude that the excita- 

 tory reaction by which the down-movement is caused is 

 relatively more intense and more quickly exhausted than 

 that which brings about the up-movement. We may gauge 

 the relative intensities of the two impulses approximately, 

 either from the maximum or the average rates of the down 



and up motions. The former gives the ratio of ~ =i'4 ; the 



latter gives n -=i-$2. The intensity of the downward 



'4 



impulse may therefore be taken to be roughly one and a-half 

 times as great as that which occasions the up-movement. 



