1917] FITZPATRICK—RHIZINA UNDULATA 293 



should be considered in any system of classification. The somewhat 

 loose use of the terms "angiocarpous" and "gymnocarpous" and 

 of the phrase "hymenium exposed from the first'' has resulted, 

 however, in some confusion. In some species (for example Leotia 

 lubrica) the ascocarp is at the beginning inclosed by an envelope 

 which is transitory and disappears before the hymenium is formed, 

 while in others (for example, Rhizina unditlata) it lacks at all stages 

 any indication of a veil. In both cases the hymenium is " exposed 

 from the first," but the development of the fruit body is essentially 

 different, and if the veil has any phylogenetic significance the two 

 forms cannot be regarded as closely related. Dodge (13) states 

 that "the real question as to whether an ascocarp is to be classed 

 as open or closed in its early stages depends upon whether the 

 young hymenial layer arises endogenously, as in Ascobolus fur- 

 furaceus, or is from the first free and exposed, as in Pyronema" It 

 seems to the writer of greater significance to determine whether 

 the ascocarp is itself at any stage inclosed by an envelope. This 

 is certainly true from the standpoint of phylogeny. 



Summary 



my 



the smaller rootlets of pines and other 

 moldlike growth. Upon this subiculum 



masses 



knobs. These constitute primordia of ascocarps. 



2. The ascocarp primordium in the youngest stages shows no 

 evidence of a sexual apparatus. It is made up of undifferentiated 

 hyphae, which at its surface form a palisade layer. 



3. The ascocarp is neither at the beginning nor at any subsequent 

 period provided with a hyphal envelope. The fruit body is there- 

 fore gymnocarpous and the hymenium is "exposed from the first." 



4. There is developed in the interior of the young ascocarp a 

 w r ell defined sexual apparatus from which the ascogenous hyphae 

 arise. The details of the sexual process have been studied and 

 will be described in a later paper. 



5. The ascogenous hyphae branch repeatedly and undergo 

 crozier formation in the development of the young asci. 



