July 22. 1875] 



NA TURE 



229 



We have here no sensitive hairs, as in the Droseracere. 

 The upper surface of the leaf is studded with glandular 

 hairs of two kinds, one with longish stalks, the other nearly 

 sessile, both of which secrete an extremely viscid fluid ; 

 and the dull irritability resides in the blade of the leaf itself, 



Fig. 5. — l^ionn'a ntjiscipula. Leaf viewed laterally in its expanded state- 



which becomes slowly incurved at the margins over sub- 

 stances that excite its sensibility (Fig. 6). This move- 

 ment of the margin of the leaves (not the apex) is caused 

 either by continued pressure from a foreign solid sub- 

 stance, or by the absorption of nitrogenous matter ; water 

 or a solution of sugar or gum produces no curvature \ and 

 although the latter, if sufficiently dense, excite a copious 

 increased flow of the viscid secretion, this has no acid 

 reaction. The increased secretion, occasioned by contact 

 of nitrogenous solids or liquids with the glands, is, on the 

 contrary, invariably acid, and possesses the power of 

 rapidly dissolving and digesting insects and other nutrient 

 substances. Some vegetable substances containing nitro- 



FiG. 6. 

 . 6. — Pingntcula 



Fig. 



ulgaris. Outline of leaf with left margin inflected 

 over a row of smal flies. 

 i'ig. 7.— Utricularia neglecta. Branch with the divided leaves be.-iring 

 bladders ; about twice enlarged. 



gen, as some seeds and pollen-grains, are acted on in a 

 similar manner, so that the butterwort is a vegetable as 

 well as an animal feeder. The secretion appears to be 

 again absorbed into the glands, together with the nutrient 

 substance dissolved in it. 

 Until thelpublication of the present volume, very little was 



known about the habits of the singular genus Utricularia or 

 Bladderwort (Fig. 7), of which several species are natives 

 of ditches, especially of very foul water, in this country. 

 The very finely divided leaves bear a number of minute 

 bladders about one-tenth of an inch in length, the form 



— Utricularia neglecta. Valve of bladder ; greatly enlarged. 



of which, as Mr. Darwin points out, bears a very singular 

 resemblance to that of a minute Entomostracan Crus- 

 tacean. Each bladder is furnished near its mouth with 

 two long prolongations, which Mr. Darwin calls "an- 

 tennae," branching into a number of pointed bristles. On 

 each side of the entrance to the bladder are also a number 

 of bristles ; and the entrance is itself almost entirely 

 closed by a movable valve (Fig. 8), which rests on a rim 

 or collar (the " peristome " of Cohn), dipping deeply into 

 the bladder, and can only open inwards. The surface of 



Fig. 9. 

 Fig. 9 —Utricularia neglecta. One of the quadrifid processes greatly 



enlarged. 

 Fig. jo.— Genlisea otnata. Portion of inside of neck leading into the 

 utricle, greatly enlarged, showing the downward pointed bristles, and 

 small quadrifid cells or processes. 



the valve is furnished with a number of glands endowed 

 with the power of absorption, but apparently not of secre- 

 tion. The whole internal surface of the bladder, with the 

 exception of the valve, is covered with a number of minute 

 bodies— the "quadrifid processes" (Fig. 9)— consisting 

 of four divergent arms of unequal length and grea 



