370 



NATURE 



[Sept. 3, 1874 



birds slit open the pitchers with their beaks to get at the contents. 

 This was probably the origin of Linnceus' statement that the 

 pitchers supplied birds with water. 



The pitchers finally decay, and part, at any rate, of their 

 contents must supply some nutriment to the plant by fertilising 

 the ground in which it grows. 



Darling/onia. — I cannot take leave of Sarracenia without a 

 short notice of its near ally, Darlingtonia, a still more wonderful 

 plant, an outlier of Sarracenia in geogi-aphical distribution, being 

 found at an elevation of 5,000ft. on the Sierra Nevada of Cali- 

 fornia, far west of any locality inhabited by Sarracenia. It has 

 pitcliers of two forms ; one, peculiar to the infant state jf the 

 plant, consists of narrow, somewhat twisted, trumpet-shaped 

 tubes, with very oblique open mouths, the dorsal lip of which is 

 drawn out into a long, slender, arching, scarlet hood, that hardly 

 closes the mouth. The slight twist in the tube causes these 

 mouths to point in various directions, and they entrap very small 

 insects only. Before arriving at a state of maturity the plant 

 bears much larger, suberect pitchers, also twisted, with the lip 

 produced into a large inflated hood, that completely arches over 

 a very small entrance to the cavity of the pitcher. A singular 

 orange-red, flabby, two-lobed organ hangs from the end of the 

 hood, right in front of the entrance, which, as I was informed last 

 week by letter from Prof. Asa Gray, is smeared with honey on its 

 inner surface. These pitchers are crammed with large insects, 

 especially moths, which decompose in them, and result in a putrid 

 mass. I have no information o'water being found in its pitchers 

 in its native country, but have myself found a slight acid secre- 

 tion in the young states of both forms of pitcher. 



The tissues of the inner surfaces of the pitchers of both the 

 young and the old plant I find to be very similar to those of 

 Sarracenia zmriolaris zxAflava. 



Looking at a flowering specimen of Darlingtonia, I was struck 

 with a remarkable analogy between the arrangement and colour- 

 ing of the parts of the leaf and of the flower. The petals are 

 of the same colour as the flap of the pitcher, and between each 

 pair of petals is a hole (formed by a notch in the opposed mar- 

 gins of each) leading to the stamens and stigma. Turning to the 

 pitcher, the relation of its flap to its entrance is somewhat similar. 

 Now, we know that coloured petals are specially attractive 

 organs, and that the object of their colour is to bring insects to 

 feed on the pollen or nectar, and in this case by means of the 

 hole to fertilise the flower ; and that the object of the flap and 

 its sugar is also to attract insects, but with a very different 

 result, cannot be doubted. It is hence conceivable that this 

 marvellous plant lures insects to its flowers for one object, and 

 feeds them while it uses them to fertilise itself, and that, this 

 accomplished, some of its benefactors are thereafter lured to its 

 pitchers for the sake of feeding itself ! 



But to return from mere conjecture to scientific earnest, I can- 

 not dismiss Darlingtonia without pointing out to you v/hat appears 

 to me a most curious point in its history ; which is, that the 

 change from the slender, tubular, open-mouthed to the inflated 

 closed-mouthed pitchers is, in all the specimens which I have 

 examined, absolutely sudden in the individual plant. I find no 

 pitchers in an intermediate stage of development. This, a 

 matter of no little significance in itself, derives additional in- 

 terest from the fact that the young pitchers to a certain degree 

 represent those of the Sarracenias with open mouths and erect 

 lids ; and the old pitchers those of the Sarracenias with closed 

 mouths and globose lids. The combination of representative 

 characters in an outlying species of a small order cannot but 

 be regarded as a marvellously significant fact in the view of those 

 morphologists who hold the doctrine of evolution. 



Nepenthes. — The genus Nepenthes consists of upwards of thirty 

 species of climbing, half shrubby plants, natives of the hotter parts 

 of the Asiatic Archipelago from Borneo to Ceylon, with a few 

 outlying species in New Caledonia, in Tropical Australia, and in 

 the Seychelle Islands on the African coast. Its pitchers are 

 abundantly produced, especially during the younger state of the 

 plants. They present very considerable modifications of form and 

 e.vternal structure, and vary greatly in size, from little more than 

 an inch to almost a foot in length ; one species, indeed, which I 

 have here from the mountains of Borneo, has pitchers which, 

 including the lid, measure a loot and a half, and its capacious 

 bowl is large enough to drown a small animal or bird. 



The structure of the pitcher of Nepenthes is less complicated 

 on the whole than that of Sarracenia, though some of its tissues 

 are much more highly specialised. The pitcher itself is here not 

 a transformed leal, as in Sarracenia, nor is it a transformed leaf, 

 blade, like that of Dionrca, but an appendage of the leaf deve- 



loped at its tip, and answers to a water-secreting gland that may 

 be seen terminating the mid-rib of the leaf of certain plants. It 

 is furnished with a stalk, often a very long one, which in the case 

 of pitchers formed on leaves high up the stem has (Ijefore the full 

 development of the pitcher) the power of twisting like a tendril 

 round neighbouring objects, and thus aiding the plant in climbing, 

 often to a great height in the forest. 



In most species the pitchers are of two forms, one appertain- 

 ing to the young, tire other to the old state of the plant, the 

 transition from one form to the other being gradual. Those of 

 the young state are shorter and more inflated ; they have broad 

 fringed longitudinal wings on the outside, which are probably 

 guides to lead insects to the mouth ; the lid is smaller and more 

 open, and the whole interior surface is covered with secreting 

 glands. Being formed near the root of the plant, these pitchers 

 often rest on the ground, and in species which do not form leaves 

 near the root they are sometimes suspended from stalks which 

 may be fully a yard long, and which bring them to the ground. In 

 the older state of the plant the pitchers are usually much longer, 

 narrower, and less inflated, and are trumpet-shaped, or even 

 conical ; the wings also are narrower, less fringed, or almost 

 absent. The lid is larger and slants over the mouth, and only the 

 lower part of the pitcher is covered witli secreting glands, the 

 upper part presenting a tissue analogous to the conducting tissue 

 ol Sarracenia, but very difierent anatomically. The difference 

 in structure of these two forms of pitcher, if considered in 

 reference to their different positions on the plant, forces the con- 

 clusion on the mind that the one for.-n is intended for ground 

 game, tlie other for winged game. In all cases tlie mouth of the 

 pitcher is furnished with a thickened corrugated rim, which 

 s rvcs three purposes : it strengthens tlie mouth and keeps it 

 distended ; it secretes honey (at least in all the species I liave 

 examined under cultivation, for I do not find tliat any other 

 observer has noticed the secretion of honey by Nepenthes), and 

 it is in various species developed into a funnel-shaped tube 

 that descends into the pitcher and prevents the escape of insects, 

 or into a row of incurved hooks that are in some cases strong 

 enough to retain a small bird, should it, when in search of water 

 or insects, thrust its body beyond a certain length into the 

 pitcher. 



In the interior of the pitcher of Nepenthes there are three 

 princip.al surfaces : an attractive, conductive, and a secretive sur- 

 face ; the detentive surface of Sarracenia being represented by 

 tl;e fluid secretion, which is here invariably present at all stages 

 of growth of the pitcher. 



Tlie attractive surfaces of Nepenthes are two : those, namely, 

 of the rim of the pitcher, and of the under surface of the lid, 

 which is provided in almost every species with honey-secreting 

 glands, often in great abundance. These glands consist of 

 spherical masses of cells, each embedded in a cavity of the tissue 

 of the lid, and encircled by a guard-ring of glass-like cellular 

 tissue. As in Sarracenia, the lid and mouth of tlii; pi.t'i.i are 

 more highly coloured than any otlier part, with the view of 

 attracting insects to their honey. It is a singular fact that the 

 only species known to me that wants tliese honey-glands on the 

 lid is the N. ampidlaria, whose lid, unlike that of the other 

 species, is thrown back horizontally. The secretion of honey on 

 a lid so placed would tend to lure insects away from the pitcher 

 instead of into it. 



From the mouth to a variable distance down the pitcher is an 

 opaque glaucous surface, precisely resembling in colour and 

 appearance the conductive surface of the Sarracenia, and, like it, 

 affording no foothold to insects, but otherwise wholly different ; 

 it is formed of a fine network of cells, covered with a glass-like 

 cuticle, and studded with minute reniforni transverse excres- 

 cences. 



The rest of the pitcher is entirely occupied with the secretive 

 surface, which consist of a cellular 'floor crowded with spherical 

 glands in inconceivable numbers. Each gland precisely resem- 

 bles a honey-gland of the lid, and is contained in a pocket of the 

 same nature, but semicircular, with the mouth downwards, so 

 that the secretive fluid all falls to the bottom of the pitcher. In 

 the Ncpoithes Jxafflcsmita 3,000 of the glands occur on a square 

 inch of the inner surface of the pitcher, and upwards of 1,000,000 

 in an ordinary sized pitcher. I have ascertained that, as was 

 indeed to be expected, they secrete the fluid which is contained 

 in the bottom of the pitcher before this opens, and that the fluid 

 is always acid. 



The fluid, though invariably present, occupies a comparatively 

 small portion of the glandular surface of the pitcher, and is col- 

 lected before the lid opens. When the fluid is emptied out of a 



