595 
Gnomonia erythrostoma , Pers. 
and general appearance as those described above in ascogonial cells. The 
difficulty of tracing the ascogonium at this period arises from the fact that 
in Gnomonia it is such a poorly differentiated structure. In spite of pro¬ 
longed search no evidence could be obtained for the development of asci 
from ascogonia, and in fact after this stage the latter cannot be traced at all. 
It would seem, therefore, that in Gnomonia the ascogonial cells are no longer 
functional. Fisch ( 15 ) states that in the allied fungus Xylaria polymorpha 
the ascogonial cells disorganize during the young stages of perithecial 
development, and that the ascogenous hyphae arise de novo . Traces of 
functionless ascogonia have also been found in Otidea aurantia (20 a) and in 
certain Lichens. 
The branches previously put out from the lower middle part of the 
ascocarp continue their growth towards the region which later becomes the 
neck of the perithecium. These branches vary considerably in width, but 
usually they are nearly as broad as the asci which are formed later. They 
are occasionally septate and are of irregular growth (Fig. 17), Their cells 
are poor in cytoplasm, and their nuclei are not to be distinguished from the 
usual vegetative nuclei. These threads disorganize before the asci come to 
maturity. The width, the irregular growth, and the early disorganization 
of these threads all indicate that they cannot be looked upon as typical 
paraphyses. In fact, Gnomonia erythrostoma has no ordinary paraphyses 
when the asci are mature. The appearance of these outgrowths is striking, 
and at first sight they suggest asci which have developed abnormally; their 
function is obscure, although they may take a part in the formation of the 
cavity of the perithecium. They do not appear to have been described 
elsewhere. 
At a later stage, short hyphae with dense cytoplasm and several deeply 
staining nuclei become distinguishable towards the base of the perithecium 
(Plates XLVIII and XLIX, Figs. 18,19). The asci invariably take their origin 
from these hyphae. Though it was difficult to obtain certainty in the matter, 
close investigation pointed strongly to the conclusion that these ascogenous 
hyphae grow out directly from vegetative cells at the base of the perithecium. 
Such a development is the natural corollary of the disappearance of the 
ascogonia in earlier stages. In the process of differentiation of the ascogenous 
cells from vegetative cells the cytoplasm becomes denser ; the nuclei become 
larger, and contain a more definite chromatin network and also a distinct 
nucleolus. No fusion has been observed prior to the formation of these 
clearly differentiated nuclei. 
The gradual increase in size of the nuclei in these ascogenous cells 
would thus appear to be due to a process of growth alone. Fig. 18 shows 
some of these nuclei which are becoming differentiated from ordinary nuclei. 
Sometimes the larger nuclei of these ascogenous cells are arranged 
irregularly in relation to each other, but more often they appear to be 
