390 M.S. B. Schnetzler on the Aériferous 
logical signification of the aériferous vesicles of the Utricularia. 
Before the researches just referred to, most botanists regarded 
them as a modification of the parenchyma of the ‘leaves, fol- 
lowing the numerous ramifications of the veins in “the form of 
a narrow band, dilating from time to time, and thus producing 
the utricles*. 
Schleiden, who studied the development of these little organs, 
saw them make their appearance at the angle of the divisions of 
the leaves, in the form of small bodies which were supported by 
short pedicels and looked like little horns. The inferior side of the 
horn and the lower margin of its aperture, which itself scarcely 
Increases in size, become much more developed than the rest, in 
such a manner that the perfect utricle forms a little rounded 
body, compressed laterally, prolonged on its upper surface on 
one side into the pedicel, and presenting on the other an aper- 
ture in the form of a funnel projecting into the interior of the 
utricle. The outer aperture of this funnel-is closed by a garni- 
ture of hairs, which form a beard attached to the superior mar- 
gin. The inner portion of the surface of the funnel is furnished 
with hairs of various and elegant forms, arranged in a perfectly 
regular manner. The whole inner surface of the utricle likewise 
bears hairs, composed of two cells, each of which is produced 
into two appendages of unequal length (Schleiden, Joc. cit.). 
Benjamin explains the formation of the utricles by aesnuey 
an arrest of development in’some segments of the leaf. Instea 
of elongating, they extend in breadth; a constriction in the 
form of a narrow neck is produced at their base, and they then 
present the form of small globular bodies attached to the neryure 
of the leaf by a short pedicel. According to Benjamin, we may 
trace the different phases of the formation of the utricles upon 
a single leaf from the base towards the apex. The utricle, at 
first filled with cytoblastema (protoplasm), becomes, by the vapid 
absorption of that liquid, a true air-reservoir. By afterwards 
extending itself in all directions, the utricle by degrees acquires 
its definitive form, which nearly resembles that of a stomach, 
the pedicel bemg placed at the pylorus and the aperture at the 
cardia; the two laterally compressed walls unite, as in a suture, 
at the eurvatura major. ‘The aperture of the complete utricle is, 
according to Benjamin, provided with a valve directed inwards. 
This valve makes its appearance, even in the earliest phases of 
the utricle, as a dark transverse band (Schacht, Beitrage, p. 28). 
Schacht (loc. cit.) shows that neither Schleiden nor Benjamin 
observed the first histogenetic phase of the utricles. The organs 
of the Utricularia called leaves by most botanists are regarded 
* G. W. Bischoff, Lehrbuch der Botanik, 1834, Bd. i. p. 167. 
