PEZIZALES 



347 



marked surface growth of their hymenia, they develop to very bizarre 

 forms. As far as known, their fructifications develop hemiangiocar- 

 pously. Thus in youth the fructifications of Hellvela elastica form small, 

 thick, hyphal tangles which gradually differentiate into stipe and pileus 

 (McCubbin, 1910). At first one of these tangles is entirely surrounded 

 by a sheath or a veil ; later this is torn and the hyphae arrange themselves 

 on the upper side of the pileus in a palisade, the future hymenium. 

 First this palisade is concave, then it expands laterally, bends up to the 

 shape of a saddle, and finally hangs down on both sides in two equal 

 lobes; between these two lobes of the hymenium project two flaps forming 

 a structure similar to that in Fig. 231, right; only in H. elastica are the 

 two lobes often unequally developed, one being often more distended 





Fig. 231. — Gyromitra infula. {After Falck, 1916.) 



than the other. As in Humaria rutilans, the ascogenous hyphae arise 

 from ordinary vegetative hyphae of the hypothecium. In Helvetia 

 crispa, pseudogamous copulations occur between these hyphae (Car- 

 ruthers, 1911). When the hooked tips of the ascogenous hyphae come 

 into open communication with the main hypha, the nucleus migrates 

 back into the hypha, forming structures similar to the clamp connections 

 of the Basidiomycetes. 



The fructifications of the other species of Helvetia at first resemble 

 those of H. elastica; even in H. ephippium the pileus is patelliform and 

 concave in youth; later it becomes saddle-shaped and finally bends down 

 in two lobes. In this species, the tips of both saddle wings are drawn out 

 to very sharp points projecting above the fructifications. In H. lacunosa 

 the fruit disc is, on account of the marked surface expansion, thinner, 

 more fragile and more variable. In order to furnish support so that it 



