Chap. XIII. TRANSMISSION OF MOTOR IMPULSE. 315 



touched towards the midrib and opposite lobe, or 

 towards the outer parts of the same lobe. 



Two slits near each other, both parallel to the mid- 

 rib, were next made in the same manner as before, one 

 on each side of the base of a filament, on five distinct 

 leaves, so that a little slip bearing a filament was con- 

 nected with the rest of the leaf only at its two ends. 

 These slips were nearly of the same size ; one was care- 

 fully measured ; it was -12 of an inch (3-048 mm.) in 

 length, and '08 of an inch (2*032 mm.) in breadth; 

 and in the middle stood the filament. Only one of 

 these slips withered and perished. After the leaf had 

 recovered from the operation, though the slits were 

 still open, the filaments thus circumstanced were 

 roughly touched, and both lobes, or one alone, slowly 

 closed. In two instances touching the filament pro- 

 duced no effect ; but when the point of a needle was 

 driven into the slip at the base of the filament, the 

 lobes slowly closed. Now in these cases the impulse 

 must have proceeded along the slip in a line parallel 

 to the ♦midrib, and then have radiated forth, either 

 from both ends or from one end alone of the slip, over 

 the whole surface of the two lobes. 



Again, two parallel slits, like the former ones, were 

 made, one on each side of the base of a filament, at 

 right angles to the midrib. After the leaves (two in 

 number) had recovered, the filaments were roughly 

 touched, and the lobes slowly closed; and here the 

 impulse must have travelled for a short distance in a 

 line at right angles to the midrib, and then have 

 radiated forth on all sides over both lobes. These 

 several cases prove that the motor impulse travels in 

 all directions through the cellular tissue, independently 

 of the course of the vessels. 



With Drosera we have seen that the motor impulse 



