The science of life : fully illustrated in tone and line and including many diagrams

THE LOWLY

treed and to float in the air in the hope of finding a new piece of dead organic matter to live on. And occasionally there is a primitive sexual process. Two threads, growing from different spores, meet at the tips and flow together to form one mass, a mass which surrounds itself with a thick, hard case and rests for awhile, ultimately to give rise to a number of spores. It is curious to note that in these lowly, creeping threads there is often a division into sexes. There are two kinds of threads, and they will only unite with members of the opposite kind. There is no outward sign of any ditference—except that one kind often grows more actively and vigorously than the other—neither do they play distinguishable parts during the actual fusion ; nevertheless, the fact that there are two strains can be made out clearly.

There is no exact distinction between fungi and alge, except that the former do not possess chlorophyll. As far as form goes, some fungi and some alge are exactly alike. The fungi may be considered as alge which have given up chlorophyll, and the independence which it confers, and taken to digesting and consuming the organic substance of other creatures instead of making their own. Bread moulds feed on dead matter, but all moulds are not so inoffensive ; some prefer their food fresh. They turn their juices against living things and become parasitic digesters of the tissues of living plants or animals.

We may note that both saprophytism (living on the decay of living things) and parasitism (living on live things) occur among plants other than fungi. The disposition to throw up honest productive work and live on the activity of other beings is as strong in the vegetable as in the animal and human worlds. Among flowering plants, for example, the bird’s-nest orchid is a saprophyte and the dodder and broom-rape are parasites. Such plants, having little or no chlorophyll, are unpleasantly pale. But these are shameful exceptions in a group of green, independent plants. The fungi, on the other hand, specialize in dependence ; every one of their multitude of species (there

Fig. 116.

AND MINUTE

are tens of thousands) is either a saprophyte or a parasite.

_ Innearly all fungi the essential living thing is a web of delicate threads, burrowing inconspicuously into the material upon which it thrives. The most conspicuous parts are the spore-bearing structures. In the common toadstools and puffballs and mushrooms, for example, the umbrella or globe or hat with which we are familiar is not the whole plant any more than an apple or a blackberry is a whole plant; it is merely the fructification, the spore-producing organ, and the essential living thing from which it sprouts is a white silken web that creeps and digests unseen in the rich soil below. The “‘ mushroom spawn ” from which edible mushrooms are grown consists of lumps of richly manured soil with this living web in it. And even a mushroom with its definite shape is not so firmly built as the body of a higher plant. There is no brick-laying, so

The germination of a mould—five stages in the sprouting of the first hypha-thread from a spore.

Very highly magnified.

to speak, of its component cells: instead of the cells being mortared together into a solid mass, it consists of an interlacement of separate hypha-strands, like a hut of interwoven branches instead of a brick house.

On the whole the fungi, like the arthropods, are malignant towards mankind. Many of the parasitic forms cause havoc among cultivated plants. ‘The rust, smut, and bunt of wheat, the diseases of potatoes, sugar-canes and larches, the destructive mildews of roses and hops and grapes—these and many other plant plagues are due to fungi parasitic in the tissue of the sufferers. A few attack our own bodies, producing ringworm and other itching affections of the skin and hair —even in civilized countries mouldy children are quite common. ‘The saprophytic forms may be troublesome, too ; there is, for example, the dry rot that undermines our buildings, as there are the moulds that spoil our food. In favour of the fungi it may be said that they are among Nature’s undertakers, helping in the decay and disintegra-

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