

THE DEVELOPMENT OF THE ASCOCARP OF RHIZINA 



UNDULATA FR. s 



Harry M. Fitzpatrick 



(WITH PLATES XVII AND XVIIl) 



Our knowledge of the earliest stages in the development of the 

 fruit body in the Helvellales is restricted to a limited number of 

 species of the Geoglossaceae and one species of the Helvellaceae. 

 Practically nothing is known of the ontogeny of any member of 

 the Rhizinaceae. The question of the origin of the h 



rmenium 



this family, therefore, is of considerable interest. 



members of 



Helvellales 



inclosing membrane. In the system of classification employed by 

 Schroter (27) the Helvellales are separated from the other orders 

 of the Discomycetes on the basis of the gymnocarpous origin of the 

 fruit body. The statement that members of this group are never 

 angiocarpous, however, was evidently based upon general obser- 

 vations rather than upon careful study of young ascocarps, and 

 subsequent investigations have demonstrated its falsity. The 

 first evidence of the presence of a veil in this group was presented 

 by Dittrich (10) in connection with investigations on the Geoglos- 

 saceae. He discovered that in the youngest stages the fruit body 

 of Leotia lubrica is inclosed by an envelope comparable to the volva 

 of the Agaricaceae. This membrane later gelatinizes and is 

 ruptured by the expansion of the ascoma within. Observations 

 made by him on Mitrula phalloides disclosed a similar condition in 

 that species. His collections of fruit bodies of representatives of 

 the Helvellaceae, including species of Helvetia and Gyromitra. 

 revealed, however, no stages young enough to shed light on the 

 question of the presence or absence of a veil in the beginning. 



Duraxd (14) in his monograph of the Geoglossaceae of North 

 America reviews the work of Dittrich on the development of 

 Leotia and Mitrula and states that observations of his own on 

 several different species point unmistakably to the same conclusion. 





Botanical Gazette, vol. 63] 



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