536 CLASS BASIDIOMYCETEAE 



colorless ellipsoid spores. There are no noticeable projections or folds on 

 the surface of the hymenial cavity and no cystidia have been observed. In 

 the absence of younger stages it is impossible to locate this with certainty. 

 Perhaps it is wiser to place this in a distinct family Protogastraceae in the 

 Order Protogastrales. (Fig. 172 A.) 



Possibly Juel's genus and family, Hemigaster and Hemigastraceae, 

 respectively, should be placed in this same order. The minute spore fruit 

 grows on rabbit excrement. It is 2 to 3 mm. tall and at maturity about as 

 broad. It arises as an upright tuft of parallel hyphae which spread at the 

 top like a sheaf of grain. The spreading hyphae curve downward and in- 

 ward and eventually join with hyphae growing out from the stipe to form 

 a circular chamber centrally pierced by the percurrent columella which is 

 in reality the upper portion of the stipe. Two layers are visible in the 

 peridium, an outer loosely woven portion and an inner denser subhy- 

 menial layer from which arise the basidia which cover the upper and outer 

 side of the circular hymenial cavity, but not the inside formed by the 

 columella. The basidia bear four nearly spherical, pale, flesh-colored 

 basidiospores with smooth surfaces. There are no cystidia or paraphyses in 

 the hymenium. From the columella there grow out into the cavity slender 

 hyphae which bear colorless chlamydospores wound about by slender 

 hyphae. Eventually the basidiospores and chlamydospores fill the cavity. 

 The mode of development of the spore fruit is of the type called pseudo- 

 angiocarpic. Since the younger stages of Protogaster are not known it is 

 not possible to determine definitely whether these two fungi are related or 

 not. Juel (1895) concluded that Hemigaster is related to the Thelepho- 

 raceae but it seems to the author that it belongs rather in the Gastero- 

 myceteae. (Fig. 172 B-D.) 



Order Hymenogastrales. These are mostly subterranean, rarely super- 

 ficial, when young, growing so as to become external at maturity in many 

 cases. The spore fruits are fleshy to cartilaginous or somewhat gelatinous. 

 The spore dispersal is not by means of digestion of the gleba into an 

 insect-visited slimy liquid or by the production of a dry mass of wind- 

 conveyed spores. The gleba retains its structure essentially till maturity 

 of the spores. The thin (or evanescent) or firm peridium surrounds a gleba 

 of uniform structure or traversed by spreading "veins" or with a central 

 columella which in one family reaches the apex, i.e., a percurrent colu- 

 mella. The development of the gleba is possibly lacunar or more often coral- 

 loid, multipileate or unipileate. By the usual classification, that of Eduard 

 Fischer (1933), four families are recognized, depending upon the type of 

 development. Many spore types are found, colorless or colored, smooth or 

 verrucose, or ribbed, etc. Possibly it may be feasible, when the youngest 

 stages of development have been studied for most of the genera, to cor- 

 relate development, spore type and mature morphology to produce a more 

 satisfactory system of classification. 



