390 M. S. B. Sclinctzlcr on the Acriferous 



logical signitication of the acriferous vesicles of the Utricularice . 

 Before the researches just referred to^ most botanists regarded 

 them as a modification of the parenchyma of the 'Jeaves, fol- 

 lowing the numerous ramifications of the veins in the form of 

 a narrow baud, 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 likewase 

 bears hairs, composed of two cells, each of which is produced 

 into two appendages of unequal length (Schleiden, he. cit.). 



Benjamin explains the formation of the utricles by assuming 

 an arrest of development in some segments of the leaf. Instead 

 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 nervure 

 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 cytoblastcma (protoplasm), becomes, by the rapid 

 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 being placed at the pylorus and the aperture at the 

 eardia; the two laterally compressed walls unite, as in a suture, 

 at the curvaiura 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 {Ice. 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, Lclubuch dcr Botauik, 1834, Bd. i. p. Uu. 



