"Plants adapt themselves to surrounding conditions," he remarked. "The oak tree in its proper latitude is tall and stately; trace it toward the Arctic circle, and it becomes knotted, gnarled, rheumatic, and dwindles to a shrub. The castor plant in the tropics is twenty or thirty feet in height, in the temperate zone it is an herbaceous plant, farther north it has no existence. Indian corn in Kentucky is luxuriant, tall, and graceful, and each stalk is supplied with roots to the second and third joint, while in the northland it scarcely reaches to the shoulder of a man, and, in order to escape the early northern frost, arrives at maturity before the more southern variety begins to tassel. The common jimson weed (datura stramonium) planted in early spring, in rich soil, grows luxuriantly, covers a broad expanse and bears an abundance of fruit; planted in midsummer it blossoms when but a few inches in height, and between two terminal leaves hastens to produce a single capsule on the apex of the short stem, in order to ripen its seed before the frost appears. These and other familiar examples might be cited concerning the difference some species of vegetation of your former lands undergo under climatic conditions less marked than between those that govern the growth of fungi here and on surface earth. Such specimens of fungi as grow in your former home have escaped from these underground regions, and are as much out of place as are the tropical plants transplanted to the edge of eternal snow. Indeed, more so, for on the earth the ordinary fungus, as a rule, germinates after sunset, and often dies when the sun rises, while here they may grow in peace eternally. These meandering caverns comprise thousands of miles of surface covered by these growths which shall yet fulfill a grand purpose in the economy of nature, for they are destined to feed tramping multitudes when the day appears in which the nations of men will desert the surface of the earth and pass as a single people through these caverns on their way to the immaculate existence to be found in the inner sphere." "I can not disprove your statement," I again repeated; "neither do I accept it. However, it still seems to me unnatural to find such delicious flavors and delicate odors connected with objects associated in memory with things insipid, or so disagreeable as toadstools and the rank forest fungi which I abhorred on earth." CHAPTER XVIII. THE FOOD OF MAN.