June 1, 1870.] 



HARDWICKE'S SCI EN CE-GO SSIP. 



129 



form a kind of fringe which, inside the pitcher, may 

 possibly be regarded as a chevaux defrise. Probably 

 it serves the purpose of a " selvage " or " hem," such 

 as ladies take care to place at the outer edge of 

 any bag they may make, for the double purpose 

 of "making a finish," and of strengthening the 

 " mouth " of the bag. 



If we examine under the microscope a narrow 

 strip of the membrane, cut from the bottom of the 

 pitcher to the top, we shall notice, first, near the 

 upper portion, an elaborate system 'of inverted 

 'pouches, or, more correctly, "hoods;" lower down 

 these are less deep, and a yellow granular mass is just 

 perceptible within each hood ; still lower we see a 

 pit or depression, each with its yellow granule, now 

 seen to be a sessile glandular hair or gland ; and at 

 the very bottom we see the sessile gland on the 



plane membrane. At first 

 sight we suppose the upper 

 hoods to be furnished with 

 a fringe, but this appear- 

 ance is illusory, and results 

 from the peculiar cuneiform 

 arrangement of chromule 

 (orange, or, more usually, 

 crimson) within the mar- 

 ginal cells. We may note 

 here that this chromule is 

 contained within the com- 

 pressed cells of what we 

 may call the cuticle of the 

 ascidium. 



We give a sketch (highly 

 magnified) of one .of the 

 " yellow granular masses," 

 found in the pouches ; they 

 are of a deep-orange colour, 

 curiously marked on the 

 exterior. With Schulz's 

 test we obtain the cellulose 

 reaction in the investing 

 membrane. Upon the gland 

 it has no effect. We treat 

 the glands as follows : — 

 Fig. 129. stages of develop- Apply chloroform, the gland 



ment of glandular system. s h r i n k s \ n s i zej but rapidly 



expands again ; the colour 

 is not destroyed, but a small 

 quantity of oil has been dis- 

 solved out. Ether and ben- 

 zole have the same effect. Millow's test gives a 

 slight albuminous reaction. Sulphuric acid (diluted) 

 has no marked effect. Nitric acid strikes a yellow 

 colour. These tests do not go to prove much ; per- 

 haps only this, that the glands have a cellulose 

 investing membrane; that the gland itself is an 

 azotized compound, and contains a limited amount 

 of essential oil, or possibly only chromule. 

 We have spoken of these granules as " glands." 



^1 



1 . Sessile hairs. 



2. Pits with sessile glands 



3. Shallow pouches. 



4. 5. Deep pouches. 

 6. Gland. 



That they really are such is beyond all doubt, and it 

 is also nearly as certain that they are identical in 

 kind and purpose with the other glandular bodies, 

 hairs or sessile glands, so plentifully distributed 

 over both surfaces of the pitcher. If we dissect 

 the membrane, we shall see that these glands are 

 connected with a subcutaneous system of vessels 

 that are more or less stained with the same orange 

 fluid (fig. 128 gives a sectional view of the mem- 

 brane), and that the .inner subcutaneous layer is 

 little else than a mass of interlaced spiral vessels. 

 The question now arises as to the function these 

 glands perform in the economy of the plant. That 

 they are, or sometime have been, of use, we need 

 not doubt, as there is no waste " pure et simple " in 

 nature. They are too numerous to be merely acci- 

 dental, their arrangement also is too regular, and we 

 may, I think, connect them with the peculiar secre- 

 tion of the pitcher. Are they then organs of excre 

 tion or secretion ? They can absorb (or secrete), as 

 may be proved by any one who will place a shrivelled 

 one in fluid ; and other experiments lead one to sup- 

 pose that they can excrete also. Of what use are 

 the fluid contents of the pitcher ? Dr. Voelcker 

 has analyzed the fluid contained in the pitcher. He 

 writes : — " The liquid was generally clear and colour- 

 less, rarely yellowish, and it reddened litmus. That 

 which was collected from different plants yielded 

 respectively 0"92, 091, 0'87, 0'02, 0"52, and 0"27 per 

 cent, of residue, which contained in 100 parts, 

 38 "61 of organic matter, consisting principally of 

 malic acid with a little citric [acid. The inorganic 

 matter contained 50'42 of chloride of potassiums 

 6'36 soda, 2"59 lime, and 2'59 magnesia. Stated in 

 a different form, an imperial gallon would contain 

 from 641 to 189 grains of solid matter in solution, 

 which is but three or four times that in ordinary 

 drinking or spring water, taking the average of each. 

 It will be observed that the organic constituents 

 are merely those which are common to many fruits, 

 and give the genial acidity to our Devonshire cider, 

 as well as to our apples, pears, and common fruits. 

 Hence we are not surprised to learn from the bo- 

 .tanical friend (Mr. John Carpenter) to whom we are 

 indebted for our specimens, and who has tasted the 

 fluid, that "it is almost tasteless, very slightly 

 sweet, but not in the least sour." He considers 

 that " thirsty travellers might drink the liquid with 

 pleasure and benefit, the more especially as, from 

 growing on trees and amongst the leaves, it would 

 be cool and refreshing." Here, then, is one possible 

 use for the fluid. The liquid is, it appears from the 

 above, slightly saccharine. Can it be that this is for 

 the purpose of attracting insects, that the fluid is 

 intended to drown them, and that our pretty Nepen- 

 thes is carnivorous ? There are plants which appear 

 to be of this character ; but we do not think it of 

 Nepenthes. The only morphological peculiarity 

 besides the fluid, which would support such a 



