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ceeding from the midrib terminate at the extreme margin of the leaf in spiral cells; but these are not so well developed as in the two preceding species. The flower-peduncles, sepals, and petals, are studded with glandular hairs, like those on the leaves.

The leaves catch many small insects, which are found chiefly beneath the involuted margins, probably washed there by the rain. The colour of the glands on which insects have long lain is changed, being either brownish or pale purple, with their contents coarsely granular; so that they evidently absorb matter from their prey. Leaves of the Erica tetralix, flowers of a Galium, scales of grasses, &c. likewise adhered to some of the leaves. Several of the experiments which were tried on Pinguicula vulgaris were repeated on Pinguicula lusitanica, and these will now be given.

(1) A moderately sized and angular bit of albumen was placed on one side of a leaf, halfway between the midrib and the naturally involuted margin. In 2 hrs. 15 m. the glands poured forth much secretion, and this side became more infolded than the opposite one. The inflection increased, and in 3 hrs. 30 m. extended up almost to the apex. After 24 hrs. the margin was rolled into a cylinder, the outer surface of which touched the blade of the leaf and reached to within the of an inch of the midrib. After 48 hrs. it began to unfold, and in 72 hrs. was completely unfolded. The cube was rounded and greatly reduced in size; the remainder being in a semi-liquefied state.

(2) A moderately sized bit of albumen was placed near the apex of a leaf, under the naturally incurved margin. In 2 hrs. 30 m. much secretion was excited, and next morning the margin on this side was more incurved than the opposite one, but not to so great a degree as in the last case. The margin unfolded at the same rate as before. A large proportion of the albumen was dissolved, a remnant being still left.

(3) Large bits of albumen were laid in a row on the midribs of two leaves, but produced in the course of 24 hrs. no effect;

nor could this have been expected, for even had glands existed here, the long bristles would have prevented the albumen from coming in contact with them. On both leaves the bits were now pushed close to one margin, and in 3 hrs. 30 m. this became so greatly inflected that the outer surface touched the blade; the opposite margin not being in the least affected. After three days the margins of both leaves with the albumen were still as much inflected as ever, and the glands were still secreting copiously. With Pinguicula vulgaris I have never seen inflection lasting so long.

(4) Two cubbage seeds, after being soaked for an hour in water, were placed near the margin of a leaf, and caused in 3 hrs. 20 m. increased secretion and incurvation. After 24 hrs. the leaf was partially unfolded, but the glands were still secreting freely. These began to dry in 48 hrs., and after 72 hrs. were almost dry. The two seeds were then placed on damp sand under favourable conditions for growth; but they never germinated, and after a time were found rotten. They had no doubt been killed by the secretion.

(5) Small bits of a spinach leaf caused in 1 hr. 20 m. increased secretion; and after 3 hrs. 20 m. plain incurvation of the margin. The margin was well inflected after 9 hrs. 15 m., but after 24 hrs. was almost fully re-expanded. The glands in contact with the spinach became dry in 72 hrs. Bits of albumen had been placed the day before on the opposite margin of this same leaf, as well as on that of a leaf with cabbage seeds, and these margins remained closely inflected for 72 hrs., showing how much more enduring is the effect of albumen than of spinach leaves or cabbage seeds.

but

(6) A row of small fragments of glass was laid along one margin of a leaf; no effect was produced in 2 hrs. 10 m., after 3 hrs. 25 m. there seemed to be a trace of inflection, and this was distinct, though not strongly marked, after 6 hrs. The glands in contact with the fragments now secreted more freely than before; so that they appear to be more easily excited by the pressure of inorganic objects than are the glands of Pinguicula vulgaris. The above slight inflection of the margin had not increased after 24 hrs., and the glands were now beginning to dry. The surface of a leaf, near the midrib and towards the base, was rubbed and scratched for some time, but no movement ensued. The long hairs which are situated here were treated in the same manner, with no effect. This latter trial was made because I thought that the hairs might perhaps be sensitive to a touch, like the filaments of Dionæa.

(7) The flower-peduncles, sepals and petals, bear glands ir general appearance like those on the leaves. A piece of a flower-peduncle was therefore left for 1 hr. in a solution of one part of carbonate of ammonia to 437 of water, and this caused the glands to change from bright pink to a dull purple colour; but their contents exhibited no distinct aggregation. After 8 hrs. 30 m. they became colourless. Two minuto cubes of albumen were placed on the glauds of a flowerpeduncle, and another cube on the glands of a sepal; but they were not excited to increased secretion, and the albumen after two days was not in the least softened. Hence these glands apparently differ greatly in function from those on the leaves.

From the foregoing observations on Pinguicula lusitanica we see that the naturally much incurved margins of the leaves are excited to curve still farther inwards by contact with organic and inorganic bodies; that albumen, cabbage seeds, bits of spinach leaves, and fragments of glass, cause the glands to secrete more freely; that albumen is dissolved by the secretion, and cabbage seeds killed by it;-and lastly that matter is absorbed by the glands from the insects which are caught in large numbers by the viscid secretion. The glands on the flower-peduncles seem to have no such power. This species differs from Pinguicala vulgaris and grandiflora in the margins of the leaves, when excited by organic bodies, being inflected to a greater degree, and in the inflection lasting for a longer time. The glands, also, seem to be more easily excited to increased secretior. by bodies not yielding soluble nitrogenous matter. In other respects, as far as my observations serve, all three species agree in their functional powers.

CHAPTER XVII.

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 bladdersUtricularia 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

* 'Beiträge zur Biologie der Pflanzen,' drittes Heft, 1875.

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