iv] HELVELLALES 



129 



In Sphaerosoma the ascophore is more or less sunk in the substratum, 

 and is attached by rooting hyphae which 

 are sometimes grouped on a short pedicel. 

 It is concave when young, but later forms 

 an irregularly globose mass over the upper 

 surface of which the hymenium is spread 

 (fig. 89). It resembles, in fact, a Pesiza 

 which becomes very much reflexed at 

 maturity. 



In Sph. Janczewskianum (fig. 88), a large Fig. 89. Sphaerosoma fu^ ts (Klotz.) 

 oogonial cell has been recognized from R Q"p-; apothecium, x6; after Roup- 

 which the ascogenous hyphae originate, 



but no details of its development are known. This genus has been variously 

 placed in the Tuberaceae and Pezizaceae as well as in its present position. 

 It shows resemblances to some of the former in its habitat under fallen 

 leaves, and to the latter group in many points of general structure. 



RHIZINACEAE : BIBLIOGRAPHY 



1909 ROUPPERT, C. Revision du genre Sphaerosoma. Bull. Acad. Sci. de Cracovie, p. 75. 

 1918 FITZPATRICK, H. M. Sexuality in Rhizina undulata Fries. Bot. Gaz. Ixv, p. 201. 



Helvellaceae 



The Helvellaceae are represented by five genera, Helvetia (fig. 900), 

 Morchella (fig. 90 &), Verpa, Gyromitra, and Cidaris ; of these the first four 

 are British. In all a definite fertile head is distinguished from the sterile 

 stalk, and over the more or less convoluted surface of the head the hymenium 

 extends. 



Development has been studied only in species of Helvetia where the 

 fruit arises as a tuft of branching, septate hyphae, and no archicarp has 

 been observed. 



In H. elasttca, young ascophores, about o - 5 mm. in diameter, show no 

 signs of fertile hyphae. A membrane of interwoven filaments encloses the 

 whole fruit body, and below this a palisade of club-shaped hyphae is differ- 

 entiated. As growth proceeds the membrane becomes broken, and the 

 palisade increases in regularity, forming the boundary of the fructification 

 except where, at the apex, the paraphyses are growing up. Later, as these 

 increase in number, the ascogenous hyphae appear among them, and 

 numerous asci are formed. 



In H. crispa the later stages of development are very similar to those 

 in H. elastica. Here nuclear fusions have been observed in the young 



