58 
MIMULUS SMITHII. 
considered mere reservoirs of water for animals, since the plants invariably grow in 
swamps and ditches where such reservoirs would he useless. Besides, the lid never 
alters its position when once raised from the pitcher, and therefore does not prevent 
evaporation, the mouth being once opened. The water contained in the pitcher is, 
for the most part, evaporated within a few days after the opening of the lid, 
although there is evidently an increased secretion during the nights, yet never to 
any considerable quantity, at least not in our stoves. Professor L. C. Treviranus, 
of Breslaw, found that when the lid of N. phyllamorphia was open, the water 
diminished one half by solar evaporation, but it was restored again at night. In 
Ceylon, Mr. Campbell informs us that animals of the Simia tribe are well 
acquainted with this plant, and frequently resort to it to quench their thirst ; still 
we can scarcely suppose this to be their destined use, for many other trees bear 
similar appendages, which could not be readily, if at all, emptied. Besides, the 
situation in which some of them grow, would render such a providential provision 
unnecessary. Whatever be their uses, there can be no doubt but they are necessary 
to the welfare and growth of the plant ; for if one be inadvertently injured, the leaf 
to which it was attached becomes sickly, and for the most part is incapable of 
performing its natural functions. 
So great a quantity of spiral vessels was discovered by Mr. Valentine in the 
stem and petioles, that no plant has yet been noticed in which they are equally 
abundant. Now, Bischoff ascertained that the air conveyed by spiral vessels 
contains about 28 per cent, of oxygen ; and, as an excessive supply of oxygen is 
destructive of vegetable life, it has been suggested that the pitchers are intended 
to rid the plant of its oxygen, and that the water they contain has been discharged 
by the spiral vessels themselves. An observation of the late Dr. Jack appears to 
favour this opinion ; for on examining the pitchers, he found their bottoms 
beautifully punctured, as if by the mouths of vessels, the same we have noticed 
ourselves. Dr. Graham states, that the water contained in some of those which he 
examined at the Botanic Garden, Edinburgh, was at the first slightly acid, and that, 
as the water evaporated, the acidity increased, until the whole had passed off. 
Dr. Turner analysed the water from an unopened pitcher, and found it to contain 
minute crystals of super- oxalate of potash ; and he says, that during the time of 
boiling, it emitted an odour like baked apples, from its containing a trace of 
vegetable matter. This may be considered as most of what is at present known 
of the uses of the appendages of Nepenthes . 
Culture of the Nepenthes. — Slight shade, heat, and moisture, are 
indispensable for the successful culture of Nepenthes. They thrive best if 
potted in chopped moss : when they are potted, plunge them in a bed of moss, 
made on the Hue of the stove, or other situation where they can receive a good 
portion of bottom heat, yet not too violent. In such a situation, they will thrive 
wonderfully, if the moss in which they are plunged be kept constantly moist, and 
