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Page:Popular Science Monthly Volume 29.djvu/622

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THE POPULAR SCIENCE MONTHLY.

hand, the man of superb ability is precocious just because, having a finer brain to start with, he is raised above the average mental stature of his years. He rather resembles a tree which shoots at once above the surrounding trees, though it may mature and bring forth fruit later than they.—Nineteenth Century.

[Concluded.]

 

WOODS AND THEIR DESTRUCTIVE FUNGI.
By P. H. DUDLEY, C. E.
II.

AT the close of my former article I described the conditions which are favorable to the growth of the fungi on woods. In this article I present a few examples under similar conditions, to show what takes place as the result of such growth.

Fig. 10 is a representation of a typical example of decay at and below the ground-line of railway-signal and telegraph poles, sign and PSM V29 D622 Decayed telegraph pole due to germinating fungi.jpgFig. 10. fence posts. In the case illustrated, as in a large number of other cases, the sap-wood forms part of the pole, the bark only being removed. At the ground-line the ever-present spores of some of the fungi have germinated, under the influence of the moisture, warmth, and air, and have sent out their delicate mycelia over the wood, the threads penetrating any season cracks or fissures, thence piercing and growing in the wood-cells; the manner of growth is not only interesting but wonderful, and almost leads one to think, for an instant, that the fungi, like animals, have instincts to protect them in their development. Certainly I do not wish to convey that impression, but rather to assert the fact of their certain growth and the consequent destruction of the wood, when the conditions before mentioned are present.

The figure shows a section from a telegraph-pole of black spruce (Picea nigra); the opening at the ground-line was sufficient for the admission of the necessary air to carry on the development of the mycelia and the fermentations, but not large enough to allow the wind and heat to dry up the moisture and check the decay; nor was the opening made until a long time after the internal decay was well advanced, the breaking away of the tissues of the wood occurring more from the inside than the outside. In unpainted poles especially of this wood so exposed to the sun that an exterior shell may be dried,