234 DION-ffiA MUSCIPULA. [Chip. XIII. 



in considerable numbers over the footstalk, the backs of the 

 leaves, and the spikes, with a few on the upper surface of the 

 lobes. These octofid projections are no doubt homologous 

 with the papillae on the leaves of Drosera rotundifolia. 

 There are also a few very minute, simple, pointed hairs,* 

 about TT^ of an inch (.0148 mm.) in length on the backs 

 of the leaves. 



The sensitive filaments' are formed of several rows of 

 elongated cells, filled with purplish fluid. They are a little 

 above the jV of an inch in length ; are thin and delicate, and 

 taper to a point. I examined the bases of several, making 

 sections of them, but no trace of the entrance of any vessel 

 could be seen. The apex is sometimes bifid or even trifid, 

 owing to a slight separation between the terminal pointed 

 cells. Toward the base there is constriction, formed of 

 broader cells, beneath which there is an articulation, sup- 

 ported on an enlarged base, consisting of diflferently shaped 

 polygonal cells. As the filaments project at right angles to 

 the surface of the leaf, they would have been liable to be 

 broken whenever the lobes closed together, had it not been 

 for the articulation which allows them to bend flat down. 



These filaments, from their tips to their bases,* are ex- 

 quisitely sensitive to a momentary touch. It is scarcely 

 possible to touch them ever so lightly or quickly with any 

 hard object without causing the lobes to close. A piece of 

 very delicate human hair, 2i inches in length, held dangling 

 over a filament, and swayed to and fro so as to touch it, did 

 not excite any movement. But when a rather thick cotton 

 thread of the same length was similarly swayed, the lobes 

 closed. Pinches of fine wheaten flour, dropped from a 

 height, produced no effect. The above-mentioned hair was 

 then fixed into a handle, and cut off so that 1 inch projected ; 

 this length being sufficiently rigid to support itself in a 

 nearly horizontal line. The extremity was then brought by a 

 slow movement laterally into contact with the tip of a fila- 



* [ThoRc hairs worn nbRont In [Ratnlln (' Flora.' 1877) auotes 

 the p'rliii'nH 'xninlnMl by Knrtz Oiidomnns (U. Academy of Sol- 

 (Relchert ami I)u Hols-Keymond's enooa of Anisterdam. IS.'iO). to the 

 Archlv.' 17C>. F. D.] effect that the tllanicnta are 



(Both FrauBtadt and De Can- much more senKltlve at the base 

 dolle describe the structure of than elsewhere. Bntallu confirms 

 these filaments, and have shown the fact fmm his own observa- 

 thnt their morphological rank Is tlons. F. D.] 



that of " emergencies." F. D.] 



