Acrospore

In all these (which to the naked eye appear as patches of a white woolly substance) the fruit, or acrospores, as they are called in technical language, are situated on the tips of certain upright threads, sometimes solitary, but more generally branched, so as to have the appearance of miniature forest trees, only that there are no leaves, and that each branchlet supports at its apex a single round or oval acrospore.

In most cases the apex of the acrospore is obtuse, and the entire body has a violet tint, more or less deep; in some it is completely colourless. These acrospores, when placed in favourable conditions, will germinate, and, in fact, comport themselves in the manner of true spores.

In the case of Empusa—for example, E. Muscee (Cohn), which attacks the common house-fly in large numbers in autumn—the yeast-like mycelial cells, at the time of the death of the insect, send forth each a tube, which bursts through the skin, and outside becomes a short club-shaped sporophore bearing a single acrospore. Each sporophore bears but one spore, and then perishes.