Cuar. XIV.) ALDROVANDA VESICULOSA. 263 
turned inwards, so that, when the lobes are closed, the 
exterior surfaces of the infolded portions come into contact. 
The edge itself bears a row of conical, flattened, transparent 
points with broad bases, like the prickles on the stem of a 
bramble or Rubus. As the rim is infolded, these points are 
directed towards the midrib, and they appear at first as if 
they were adapted to prevent the escape of prey; but this 
can hardly be their chief function, for they are composed of 
very delicate and highly flexible membrane, which can be 
easily bent or quite doubled back without being cracked. 
Nevertheless, the infolded rims, together with the points, 
must somewhat interfere with the retrograde movement of 
any small creature, as soon as the lobes begin to close. The 
circumferential part of the leaf of Aldrovanda thus differs 
greatly from that of Dionsa; nor can the points on the rim 
be considered as homologous with the spikes round the leaves 
of Dionza, as these latter are prolongations of the blade, and 
not mere epidermic productions. They appear also to serve 
for a widely different purpose. 
On the concave gland-bearing portion of the lobes, and 
especially on the midrib, there are numerous long, finely 
pointed hairs, which, as Prof. Cohn remarks, there can be 
little doubt are sensitive to a touch,* and, when touched, 
cause the leaf toclose. They are formed of two rows of cells, 
or, according to Cohn, sometimes of four, and do not include 
any vascular tissue. They differ also from the six sensitive 
filaments of Dionza in being colourless, and in having a 
medial as well as a basal articulation. No doubt it is owing 
to these two articulations that, notwithstanding their length, 
they escape being broken when the lobes close. 
The plants which I received during the early part of 
October from Kew never opened their leaves, though sub- 
jected toa high temperature. After examining the structure 
of some of them, I experimented on only two, as I hoped that 
the plants would grow; and I now regret that I did not 
sacrifice a greater number. 
A leaf was cut open along the midrib, and the glands 
examined under a high power. It was then placed in a few 
drops of an infusion of raw meat. After 3 hrs, 20 m. there 
* [In a paper in the ‘Nuovo Gior- case, namely that the irritability 
nale Botanico Italiano,’ vol. viii. 1876, resides exclusively in the central 
p- 62, Mori states that this is the glandular region of the leaf—F, D.] 
