314 DION^A MUSCIPULA. Chap. XIII. 



tissue) seems at first sight to fayour tliis belief; for 

 they run up the midrib in a great bundle, sending 

 off small bundles almost at right angles on each side. 

 These bifurcate occasionally as they extend towards 

 the margin, and close to the margin small branches 

 from adjoining vessels unite and enter the marginal 

 spikes. At some of these points of union the vessels 

 form curious loops, like those described under Drosera. 

 A continuous zigzag line of vessels thus runs round 

 the whole circumference of the leaf, and in the midrib 

 all the vessels are in close contact ; so that all parts of 

 the leaf seem to be brought into some degree of com- 

 munication. Nevertheless, the presence of vessels is 

 not necessary for the transmission of the motor 

 impulse, for it is transmitted from the tips of the 

 sensitive filaments (these being about the -^ of an 

 inch in length), into which no vessels enter ; and 

 these could not have been overlooked, as I made thin 

 vertical sections of the leaf at the bases of the fila- 

 ments. 



On several occasions, slits about the -^ of an inch 

 in length were made with a lancet, close to the bases 

 of the filaments, parallel to the midrib, and, there- 

 fore, directly across the course of the vessels. These 

 were made sometimes on the inner and sometimes 

 on the outer sides of the filaments ; and after several 

 days, when the leaves had reopened, these filaments 

 were touched roughly (for they were always rendered 

 in some degree torpid by the operation), and the 

 lobes then closed in the ordinary manner, though 

 slowly, and sometimes not until after a considerable 

 interval of time. These cases show that the motor 

 impulse is not transmitted along the vessels, and they 

 further show that there is no necessity for a direct 

 line of communication from the filament v/hich is 



