Chap. XIII.] SENSITIVENESS OF FILAMENTS. 233 



The margins of the leaf are prolonged into sharp rigid pro- 

 jections which I will call spikes, into each of which a bundle 

 of spiral vessels enters. The spikes stand in such a position 

 that, when the lobes close, they interlock like the teeth of a 

 rat-trap. The midrib of the leaf, on the lower side, is strong- 

 ly developed and prominent. 



The upper surface * of the leaf is thickly covered, except- 

 ing towards the margins, with minute glands of a reddish or 

 purplish colour, the rest of the leaf being green. There are 

 no glands on the spikes, or on the foliaceous footstalk. The 

 glands are formed of from twenty to thirty polygonal cells, 



Fro. 12. 



(Dioniea mnscipula.) 



Leaf viewed laterally in its expanded state. 



filled with purple fluid. Their upper surface is convex. 

 They stand on very short pedicels, into which spiral vessels 

 do not enter, in which respect they differ from the tentacles 

 of Drosera. They secrete, but only when excited by the 

 absorption of certain matters; and they have the power of 

 absorption. Minute projections, formed of eight divergent 

 arms of a reddish-brown or orange colour, and appearing 

 under the microscope like elegant little flowers, are scattered 



[A. Fraustaclt, In his Rreslau tlons the same fact. It Is easy to 

 dissertation on Dlonaea (Mar. see that the lower surface of the 

 1876) states that the upper sur- leaf is a better one for the de- 

 face of the leaf is devoid of velopment of stoinata than the 

 stomata. C. De Cnndolle, upper surface, which Is liable to 

 ' Archives des Sciences IMiys. et l)e constantly bathed In secre- 

 Nat.' Geneva, April, 1876, men- tlon. F. D.] 



