448 CLASS BASIDIOMYCETEAE 



live the nonparasitized ones, but never reproduce. The newly hatched 

 young from the unparasitized insects, in creeping around to find a place to 

 settle down come in contact with the germinating basidiospores and the 

 yeast-like buds from the latter adhere to the body or appendages of the 

 insects. Many of the young escape infection so that there are always 

 enough left to reproduce the species while the others feed the fungus which 

 provides the sheltering homes for them. The chief genus is Septobasidium, 

 with over 160 species and subspecies. They are reported from both the 

 Old World and the New World, especially in tropical and subtropical 

 regions, but extend up into the warmer temperate regions. One species 

 grows in Canada. None are known in the colder parts of Europe and Asia. 

 Vast areas of the world are still only slightly studied with this genus in 

 view. The typical basidium consists of a well-developed, rather firm- 

 walled hypobasidium from which grows out the straight or curved epi- 

 basidium which becomes four-celled. In some species new basidial 

 primordia proliferate in the empty hypobasidia. The basidiospores are 

 borne on well-developed sterigmata. They usually become septate after 

 discharge and then apparently germinate only by yeast-like buds and not 

 by hyphae. In many species the hypobasidium is dark-colored and serves 

 as a resting spore until favorable conditions arise, in others the wall is 

 hyaline and the epibasidium develops immediately. Boedijn and Stein- 

 mann (1931) were the first to report that in some species of the genus no 

 distinction of hypobasidium and epibasidium can be observed. In many 

 species the basidium is one-celled, two-celled, or three-celled, with or 

 without a distinct hypobasidium. The mycelium lacks clamp connections, 

 both on the hyphae external to or within the bodies of the insect hosts. In 

 the latter the hyphae are a series of slender spindle-shaped cells with or 

 without thick, coiled or clumped haustoria. The fungus forms a two-, or 

 more, storied structure with chambers in which the insects live, and tun- 

 nels. In some species definite pillars support the successive layers of the 

 fungus. Growth may cease in unfavorable times and become renewed 

 when favorable weather recurs. The presence of a scale insect often in- 

 duces the fungus to form a house or tent above it, but often only a low 

 vaulted cavity is developed over the insect. The tunnels and openings to 

 the surface provide means of egress for the young insects. The upper layer 

 consists of more or less vertically growing loose hyphae, usually branched 

 at intervals, and bearing the basidia at the surface. In a number of species 

 conidia have been observed, usually produced on the floor of the tunnels 

 or chambers or on short branches from the ascending hyphae of the upper 

 layer. (Fig. 147.) 



The Septobasidium colony may be but a few millimeters in diameter or 

 up to 20 or 30 cm. or more. It may be a fraction of a millimeter in thick- 

 ness or up to 1 cm., depending upon the species. It often resembles a lichen 



