1917] FITZPATRICK—RHIZINA UXDULATA 291 



paraphyses and palisade hyphae at the point of contact never 

 being very sharp. Fig. 9 pictures approximately one-half of a 

 median longitudinal section through an older fruit body in which 

 the layer of paraphyses has become sharply differentiated from the 

 tissue of the fruit body below. The rounded sterile margin of the 



f apothecium is here evident. 



, Ascogenous hyphae. — Immediately beneath the paraphyses is 

 a deeper-staining zone filled with the ultimate tips of the profusely 

 branching ascogenous hyphae. These hyphae have their origin 

 near the base of the fruit body in the sexual apparatus previously 

 mentioned, and may be seen ramifying throughout the interior of 

 the ascocarp as they branch and rebranch on their upward journey 

 toward the hymenium. ' At this stage these threads have not yet 

 undergone crozier formation at their tips, and no young asci are 

 present. Fig. 12 shows a section through the hymenium of a more 

 mature apothecium in which the young asci are pushing up among 

 the paraphyses. The septate paraphyses, the tubular setae, and the 

 oung, deep-staining, clavate asci show here to good advantage. 

 In fig. 13 the asci are shown at about one-half their mature size, 

 and the fusion nucleus may clearly be seen in each. In this and 

 other sections the deep-staining glutinous secretion previously 

 discussed forms a well defined layer above the clavate tips of the 



paraphyses. 



General considerations 



The results of the present investigation on the origin and devel- 

 opment of the ascocarp in Rhizina undulata are particularly interest- 

 ing in the light of the facts disclosed by various workers on other 

 allied forms. Before the publication of the work of Dittrich 

 (10) on the development of Leotia lubrica and Mitrula phalloides, 

 it was generallv assumed that in the 3 families of the Helvellales 



v 



the fruit body is gymnocarpous. After the appearance of Dit- 

 trich 's paper the pendulum of opinion swung to the other extreme, 

 and we find the statement made by Durand (14) that in his 

 opinion "when the development of the Discomycetes shall be 

 better understood it will be found that in none of them, not even 

 in the Helvellaceae, is the hymenium 'exposed from the first/" 

 It is evident now from the results of researches on various 



