470 



COMPARATIVE MORPHOLOGY OF FUNGI 



authors to place this genus in the Sclerodermataceae. It seems to be 

 a transition form in many of its characters but it has not been investigated 

 ontogenetically nor cytologically. 



In Leucogaster we have another interesting genus, perhaps even more 

 primitive than Rhizopogon. As in R. rubescens, the cavities develop 

 centrifugally from the ground tissue. In L. floccosus the cavities are first 

 filled by spores borne acrogenously on short branches of zigzag hyphae, 

 or sometimes terminally on large hyphae springing from the trama. 

 These consititute the Leucophlebs stage which is also known in L. odoratus, 

 L. foveolatus and L. citrinus. If these are not disseminated they disinte- 

 grate in situ, filling the cavity with a dilute gel into which the basidia 

 penetrate. The basidia are sometimes long pedicellate, pyriform, often 

 with pedicels 200 to 300^1ong, and solitary in L. araneosus and L. rubescens. 

 In other species, as those of Europe and L. citrinus of California and 

 Australia, the basidia are short and united into compact hymenia. The 



*a«*- 



Fig. 298. — Scleroderma vulgare. A section of young fructification. B. Portion of gleba. 



(After Tulasne.) 



spores are very highly sculptured and enclosed in a gelatinous sheath. 

 A true peridium is only developed in L. luteomaculatus and even here 

 it is not so highly differentiated as in some species of Rhizopogon. Many 

 features of this genus are suggestive of the Sclerodermataceae, but 

 unfortunately it has been little studied. 



It is possible that other genera which have not yet been studied 

 ontogenetically may belong here, but such fragmentary statements as 

 have been made lead one to classify them elsewhere for the present. 



Sclerodermataceae. — This family includes a group of simple forms 

 with a simple peridium which splits irregularly at maturity (except in 

 Scleroderma Geaster) and a chambered gleba, penetrated by a slightly 

 developed capillitium, and becoming dusty at maturity. The fructifi- 

 cations of S. Bovista and S. vulgare are usually epigaeous, arising laterally 

 or terminally on mycelial threads, from a homogeneous tissue of thin- 

 walled, tangled hyphae which radiate toward the periphery. These 



