The true mushroom itself is to a great extent a dung-borne species, therefore mushroom-beds are always liable to an invasion from other dung-borne forms. The spores of all fungi are constantly floating about in the air, and when the spores of dung-infesting species alight on a mushroom-bed they find a nidus already prepared that exactly suits them; and if the spawn of the new-comer becomes more profuse than that of the mushroom the stranger takes up his position at the expense of the mushroom.
The town perhaps occupies the site of the ancient Nidus or Nidum of the Romans on the Julia Maritima from which a vicinal road branched off here for Brecon.
The custom of providing a material abode or nidus for the ghost;s found all over the earth; e.g.
Their fortuitous dissemination does not always bring seeds upon a suitable nidus for germination, the primary essential of which is a sufficiency of moisture, and the duration of vitality of the embryo is a point of interest.
Nidus has given the scientific term for nest-building, nidification.
The issue of the struggle was not a complete victory even in Byzantium for the partisans of image-worship. The iconoclasts left an indelible impress on the Christian art of the Greek Church, in so far as they put an end to the use of graven images; for the Eastern icon is a flat picture, less easily regarded than would be a statue as a nidus within which a spirit can lurk.