Chapter 17

UTRICULARIA.

Utricularia neglecta--Structure of the bladder--The uses of the several parts--Number of imprisoned animals--Manner of capture--The bladders cannot digest animal matter, but absorb the products of its decay--Experiments on the absorption of certain fluids by the quadrifid processes--Absorption by the glands--Summary of the observation on absorption-- Development of the bladders--Utricularia vulgaris--Utricularia minor--Utricularia clandestina.

I WAS led to investigate the habits and structure of the species of this genus partly from their belonging to the same natural family as Pinguicula, but more especially by Mr. Holland's statement, that "water insects are often found imprisoned in the bladders," which he suspects "are destined for the plant to feed on."* The plants which I first received as Utricularia vulgaris from the New Forest in Hampshire and from Cornwall, and which I have chiefly worked on, have been determined by Dr. Hooker to be a very rare British species, the Utricularia neglecta of Lehm. I subsequently received the true Utricularia vulgaris from Yorkshire. Since drawing up the following description from my own observations and those of my son, Francis Darwin, an important memoir by Prof. Cohn

*The 'Quart. Mag. of the High Wycombe Nat. Hist. Soc.' July 1868, p. 5. Delpino ('Ult. Osservaz. sulla Dicogamia,' &c. 1868-1869, p. 16) also quotes Crouan as having found (1858) crustaceans within the bladders of Utricularia vulgaris.

I am much indebted to the Rev. H.M. Wilkinson, of Bistern, for having sent me several fine lots of this species from the New Forest. Mr. Ralfs was also so kind as to send me living plants of the same species from near Penzance in Cornwall.

on Utricularia vulgaris has appeared;* and it has been no small satisfaction to me to find that my account agrees almost completely with that of this distinguished observer. I will publish my description as it stood before reading that by Prof. Cohn, adding occasionally some statements on his authority.

FIG. 17. (Utricularia neglecta.) Branch with the divided leaves bearing bladders; about twice enlarged.

Utricularia neglecta.--The general appearance of a branch (about twice enlarged), with the pinnatifid leaves bearing bladders, is represented in the above sketch (fig. 17). The leaves continually bifurcate, so that a full-grown one terminates in from twenty to thirty

* 'Beitrage zur Biologie der Plflanzen' drittes Heft, 1875.

points. Each point is tipped by a short, straight bristle; and slight notches on the sides of the leaves bear similar bristles. On both surfaces there are many small papillae, crowned with two hemispherical cells in close contact. The plants float near the surface of the water, and are quite destitute of roots, even during the earliest period of growth.* They commonly inhabit, as more than one observer has remarked to