Chap. XVI.] PINGUICULA VULGARIS. 299 



of 18 inches; but the fluid in this case was secreted by a 

 gland which had been excited. The edge of the leaf is trans- 

 lucent, and does not bear any glands; and here the spiral 

 vessels, proceeding from the midrib, terminate in cells 

 marked by a spiral line, somewhat like those within the 

 glands of Drosera. 



The roots are short. Three plants were dug up in North 

 Wales on June 20, and carefully washed; each bore five or 

 six unbranched roots, the longest of which was only 1.2 of an 

 inch. Two rather young plants were examined on Septem- 

 ber 28; these had a greater number of roots, namely eight 

 and eighteen, all under 1 inch in length, and very little 

 branched. 



I was led to investigate the habits of this plant by being 

 told by Mr. W. Marshall that on the mountains of Cumber- 

 land many insects adhere to the leaves. 



A friend sent me on June 23 thirty-nine leaves from North Wales, 

 which were selected owing to objects of some kind adhering to 

 them. Of these leaves, thirty-two had caught 142 insects, or on an 

 average 4.4 per leaf, minute fragments of insects not being in- 

 cluded. Besides the insects, small leaves belonging to four diflfer- 

 ent kinds of plants, those of Erica tetralix being much the com- 

 monest, and three minute seedling plants, blown by the wind, 

 adhered to nineteen of the leaves. One had caught as many as ten 

 leaves of the Erica. Seeds or fruits, commonly of Carex and one 

 of Juncus, besides bits of moss and other rubbish, likewise adhered 

 to six of the thirty-nine leaves. The same friend, on June 27, 

 collected nine plants bearing seventy-four leaves, and all of. these, 

 with the exception of three young leaves, had caught insects; 

 thirty insects were counted on one leaf, eighteen on a second, and 

 sixteen on a third. Another friend examined on August 22 some 

 plants in Donegal, Ireland, and found insects on 70 out of 157 

 leaves; fifteen of these leaves were sent me, each having caught 

 on an average 2.4 insects. To nine of them, leaves (mostly of 

 Erica tetralix) adhered; but they had been specially selected on 

 this latter account. I may add that early in August my son found 

 leaves of this same Erica and the fruits of a Care.x on the leaves of 

 a Pinguicula in Switzerland, probably Pinguicula alpina : some in- 

 sects, but no great number, also adhered to the leaves of this plant, 

 which had much better developed roots than those of Pinguicula 

 vulgaris. In Cumberland, Mr. Marshall, on September 3, carefully 

 examined for me ten plants bearing eighty leaves; and on sixty- 

 three of these {i.e. on 79 per cent.) he found insects, 143 in num- 

 ber; so that each leaf had on an average 2.27 insects. A few days 

 later he sent me some plants with sixteen seeds or fruits adhering 

 to fourteen leaves. There was a seed on three leaves on the some 



