TQE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[THIRD SERIES.] 

 No. 120. DECEMBER isn;. 



XLVI. — Observations on the Acrlferous Vesicles of the Utricu- 

 larire. By S. 13. Schnetzler^'. 



The genus Utricularia consists of aquatic plants which we find 

 in the sta^^nant waters of ditches, mai-shes, &c. The leaves ai-e 

 submerged^ and divided into fine lacinire furnished with vesicles 

 or utricles [asci). The follow'ing is the function ascribed by 

 De Candolle to these organs. 



These utricles are rounded and furnished with a sort of move- 

 able operculum. During the youth of the plant they are filled 

 with a mucilage which is heavier than water; and the plant, 

 held down by this ballast, remains at the bottom. Towards the 

 period of flowering, the leaves secrete a gas wliicli makes its way 

 into the utricles, and drives out the mucilage by raising the 

 operculum ; the plant, then furnished with a multitude of air- 

 bladders, rises slowdy, and at last floats at the surface. The 

 flowering takes place in the open air; and as soon as it is com- 

 pleted the leaves resume the secretion of mucilage, which re- 

 places the air in the utricles; the plant again becomes heavier, 

 and descends to the bottom of the water, in order to ripen the 

 seeds in the very place where they have to be sownf- 



Notwithstanding the investigations of GoppertJ, Benjamin §, 

 Schleideu ||, Schacht^, Rcinsch **, &c., botanists have not yet 

 arrived at a complete agreement as to the origin and morpho- 



* Translated by AV. S. Dallas, F.L.S., from the ' Bibliotheque Uuiver- 

 scllc,' tome xxix. August 2.5, 186/, pp. 2.96-311. 



t De Cumlolle, ' Physioiogie vegetale,' tome ii. p. 9^7 • 



X Botanische Zeitnng, 1847, P- 721. I have uot seen this work. 



§ Ibid. 1848, p. 17. 



II Gruudziige dcr wissenschaftlichen Botanik, 4th edit. p. 388. 



^ Beitrage zur Anatovnie uml Physioiogie, 1851, p. 28. 



** Deukschrifteu dcr kou. Bayer", but. Gesellsch. 1859, Bd. iv. ]i. 153 

 (I have not been able to procure this memoir); Reiusch, Das Mikroscop, 

 1867. 



Ann. ^ Mag. N. Hist. Ser. 3. Vul.xx. 27 



