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84 chlorophyll, is never seen in any Fungi. With some exceptions, the Fungi nourish themselves on organic matter, whereas plants combine inorganic matter, such as water, carbonic acid, ammonia, phosphates, etc., assimilating these principles in their growth. The life-processes, the absence of amylum and chlorophyll, are such important facts in the economy of the Fungi that some naturalists deny that they are plants at all, and wish to place them in the intermediate kingdom referred to in the preceding chapter. The reproduction of the Fungi, and the many transitional forms hardly distinguishable from Algae and Lichens, influence most botanists in regarding them as very aberrant, but still members of the vegetal kingdom.

Most Fungi are parasitic in their mode of existence, living at the expense of the plant or animal on which they are found.

The disease known as scald-head is due to the presence of a fungus, the Achorion; the thrush, a throat trouble, is caused by a fungus, the Oidium. Quite a flora has been described by Leidy and Robin as existing in the intestines of different animals, consisting principally of Fungi. The Fungi are found, however, in the greatest profusion on decaying vegetal matter, stumps of trees, etc. being converted into powder by them. When half-eaten fruit is allowed to stand, soon it is seen to be covered with a whitish film, which, when examined under the microscope, is found to be made up of the filaments of a Fungus. A Fungus, while essentially cellular, consists of two parts, the mycelium, or threads, and the colorless spores, or fruit: the threads are elongated cells, and resemble in position the stems of higher plants; the spores are seen at the end of the threads. (See Fig. 103, Grape Fungus.) The spores are sometimes free (stylospores), or they are inclosed in what is called an ascus. (See figure of Stilbospora and Sphaeria, Fig. 104, b, c.) The arrangement of the spores