Morphology of Conidiobolus Villosus

Abstract

The fungus described in this note appeared in July, I923, on a plate of nutrient agar inoculated from a piece of very rotten wood. This wood, collected in a moist thicket on the banks of the Iowa River, was covered with a brown Hypocknus, and an attempt was made to secure the latter in pure culture. Other fungi, especially the one here considered, grew so rapidly in the cultures that the attempt was abandoned, and the original collection discarded, before it was realized that the most conspicuous contamination was an undescribed species of Conidiobolus. It was readily secured in pure culture, and proved itself capable of developing an extensive myceliumr with great rapidity on ordinary nutrient media. On solid media the hyphae are of rather uniform size, averaging I2 ,ut in diameter and branching rather sparingly. When growing in a liquid medium, variation in size is greater and branching may be profuse. In either instance considerable difference in this respect may be due to the medium. Hyphae immersed in prune decoction, for example, branch much less freely than those growing in a decoction made from fresh green beans (text fig. i). Growth is vigorous in both instances. As the hyphae grow, the older parts tend to become emptied of protoplasm, and cut off by septa from the protoplasm-filled tip. Frequently a septum appears before the protoplasm is all withdrawn, and-in this way numerous segments are isolated, filled with protoplasm, with emptied and shrunken hyphal portions on either side (fig. 8 c). If food is abundant, these segments may send out lateral branches almost at once (fig. 20). In old and exhausted or dried cultures they tend to remain dormant and to accumulate, assuming various enlarged shapes, and forming hyphal bodies entirely homologous with the well known structures to which that name is applied, formed by the Entomophthoraceae attacking insects (fig. i9 a-f). In the species under consideration, however, these hyphal bodies