confluens and the Morphology of the Ascocarp. 383 
production from the period after, to that just preceding 
fertilization. 
If we attempt to compare the sexual organs and the 
ascus-fruit of Pyronema with the reproductive organs in 
other Fungi and Algae, the fundamental resemblance in the 
process here to what we find in the Lichens as described by- 
Stahl and other authors noted above, is at once apparent. 
De Bary (13) has already discussed this resemblance fully 
but without a knowledge of the behaviour of the contents 
of the sexual cells in the fertilization of Pyronema. The fact 
that the basal wall of the conjugating tube is broken down 
for fertilization strengthens the resemblance between this 
organ and the trichogyne of the Lichens. To be sure, the 
actual fertilization has not yet been observed in any Lichen, 
still the morphological significance of the organs concerned 
is established beyond question. That the trichogyne should 
be a multicellular hypha is remarkable; but the fact that the 
entire mass of antheridial nuclei does migrate through a con¬ 
necting tube to the oogonium in the case of Pyronema , makes it 
less difficult to assume the correctness of Stahl’s interpretation 
of the structures in the Lichens. The fertilization in the 
Lichens consists presumably in the fusion of a single pair of 
sexual nuclei, but this cannot affect the question of the 
homology of the parts as I think I have shown above. 
The resemblance between Pyronema and the red Algae 
is certainly very striking. The tubular trichogyne which is 
simply a prolongation of the oogonium of Nemalion or Ba - 
trachospermum is strikingly similar to the conjugating tube 
in Pyronema. Davis (10) has endeavoured to show that the 
trichogyne of Batrachospermum is a distinct cell. His results 
are opposed by Schmidle (31) and Osterhout (27) who deny 
the existence of a nucleus in the trichogyne. But in any 
case the homologies would not be affected. The trichogyne 
in Pyronema is an outgrowth of the oogonium, and it would 
make little difference in its morphological significance whether 
a cross-wall were put in between the two or not, though the 
development of this wall is of considerable functional impor- 
