208 Dynamic Theory. 



Like many of the parasitic worms, certain Fungi, possess alternate 

 forms of reproduction; form a, for example, producing spores that 

 sprout into form l>, quite different from a. But the spores produced by 

 b will, upon germination, develop into a, &c. Sometimes there "are 

 three or four terms instead of two. The red rust of wheat and grasses 

 reproduces the corn mildew. 



Again, many species possess several forms of reproductive organs 

 and several sorts of fruit, apparently from the same mycelium, and in 

 some cases it is pretty well proved. In all these particulars low forms 

 of animal life are found to imitate these fungi. 



There are some fungi that do not propagate by means of spores. 

 Their entire structure consists of similar cells, and they reproduce by 

 fission, or the division of cells, and so never develop by the metagenesis 

 or alternate generation ( for such it is ) of seeds or spores. Such a plant 

 is the Torula. 



A singular feature of the Fungi is their choice in the matter of the 

 host they shall patronize, the same kinds of fungus having become dif- 

 ferentiated to the same mode of life and the same food. Several differ- 

 ent kinds live on wheat and the grasses. One, Puccinia, specialty favors 

 Indian corn, another attacks celery, and a third plum leaves. The 

 Peronospora infestans is the potato fungus, while other varieties of the 

 same affect spinach, onions, lucerne, &c. One, Oidium, attacks grape- 

 vines, while another attends to hop-vines. The Ascomyces deformans 

 lives on peach leaves ; a Bullatus on pear leaves ; a Juglandis on walnut 

 leaves ; a Pruni on plum fruits. Some species live on the cotton plants 

 of India, while one, Torula, confines itself to the unripe pods. In short, 

 scarcely a plant can be named that does not have its favorite mould, rust 

 or mildew. But the fungi do not confine their operations to plants, liv- 

 ing or dead. They are found at times on bone, horn, leather, &e. , and 

 many varieties find a living on live animals of all sorts. A white 

 mould is very destructive to the common house-fly. Another envelops 

 with its growth, spiders, wasps, moths and butterflies, and many dead 

 insects are found covered with mould under circumstances that indicate 

 the mould as the cause of their death. Many diseases of man and other 

 animals arise from these vegetable parasites. The water-brash plant, 

 Sarcina Ventriculi, found in the fluid of that disease, is an example. 

 Tetter and ringworm are due to a fungus, and so it is supposed is the 

 disease of the hair called Plica Polonica. The so-called germ diseases 

 belong to the same class ( see Chap. 31 ). 



On the other hand, the fungi furnish food to a good many little ani- 

 mals of various kinds. And again, a certain section of them, under the 

 name of Ferments, render service to man that could not be dispensed 

 with. It is a question how far the various sources of living affected bv 



