358 Fraser. — On the Sexuality and Development of 
forms as the Laboulbeniaceae, and that the Discomycetes may have been 
thence developed through Pyrenomycetous ancestors. 
The multicellular ascogonium of Physcia has been found by Darbi- 
shire ( 9 ) to be practically a coenogamete, its uninucleate cells being 
connected by broad strands of protoplasm. In Ascobolus also, where the 
individual cells of the ascogonium are multinucleate, the walls between 
them are incompletely formed (Harper ( 16 ), and in Boudiera (Claussen (6)) 
they do not develop until after fertilization. 
A series might thus be outlined, passing to Lachnea stercorea , where 
the walls of the ascogonium are not developed, and thence to Pyronema , 
where the now useless septa of the trichogyne are also lost. Humaria 
gramdata would represent a side branch, passing out from the neighbour- 
hood of Lachnea stercorea , possibly through L. scutellata (Woronin ( 22 )). 
A serious difficulty, however, in the way of any such series, whether it 
pass from the Pyronemaceae to the Laboulbeniaceae, or in the opposite 
direction, is the structure of the male organs. It may indeed be possible 
to relate the female organs of the group, but it is far more difficult, in the 
present state of our knowledge, to derive the spermogonium from the 
antheridium or vice versa, or to imagine stages by which the one may have 
replaced the other. 
Further, it is of course perfectly possible that the multicellular 
trichogyne may have arisen separately in different groups of the Asco- 
mycetes in response to similar needs. 
Summary. 
1. The archicarp of Lachnea stercorea consists of several cells and 
terminates in a large, multicellular ascogonium. 
2. From the ascogonium a trichogyne, which is at first unicellular, but 
eventually consists of four, five, or six coenocytic cells, grows out. Its 
terminal cell is much larger than the others and may become continuous 
with the antheridium. 
3. The antheridium, which is not always fully developed, is a uni- 
cellular coenocytic sac ; its origin could not be traced with certainty. 
4. The male nuclei do not reach the ascogonium, but fertilization of 
a reduced type occurs, the female nuclei fusing in pairs. 
5. Ascogenous hyphae, into which the fused nuclei pass, grow out 
from the ascogonium, and asci are formed, by the usual method, at their tips. 
6. Lachnea stercorea is intermediate, with regard to its sexuality, 
between Pyronema confiuens on the one hand and Humaria gramdata on 
the other, and with regard to the organization of its trichogyne, between 
Pyronema and certain of the Pyrenomycetes. 
October , 1906. 
