Studies in ascostromatic lichen-fungi-I. The problem of Ascohymeniales and Ascoloculares

The hyphal elements in the hymenium of the mature ascocarp do not provide a reliable means of distinguishing an ascohymenial ascocarp from an ascostroma. The nature of these hyphal elements is determined by neither their shape nor their tips but solely by their origin. Furthermore, since it has not yet been proved that there is any relation between the structure of the ascus and the type of development of the ascocarp, the kind of ascus is of relatively little value as a means of determining the developmental type of the ascocarp. Moreover, it is often practically impossible to decide whether an ascus is bitunicate or not. The author does not know of any other feature that is a reliable indicator of the true nature of the ascocarp. Therefore, he sees no other means of determining the group to which the ascocarp is to be referred except to study its mode of development.