3 70 Notices of Books and Papers . 
looked like the beginnings of either apothecia or pycnidia, more 
probably the latter. In some species, as Lecanora subfusca , the 
hyphae radiate from the spore in a horizontal plane, forming what was 
called by the older lichenologists a hypothallus. Later on, the 
branches of the hyphae are vertical, and a proper thallus arises in 
which, in some species, a proper cortical layer is formed. The very 
slow rate of growth is shown by the fact that, at the end of three 
months, the thalli of Z, subfusca were only from 1*5 to 2 mm. in dia- 
meter, while in Opegrapha subsiderella the growth was much slower. 
Closely related species, however, vary very much in their rate of 
growth, for, while in Opegrapha it was extremely slow, in Graphis 
scripta it was comparatively rapid. 
The second point of interest is that, in several of the species studied, 
the spermatia when cultivated gave out hyphae which formed thalli 
similar to those produced by the spores. On this point Dr. Moeller’s 
observations are conclusive, although it is perhaps a little premature 
to say that the spermatia of all lichens are of the nature of conidia 
and will germinate under favourable conditions. Analogy would lead 
us to suppose that this is the case, but in a question of this kind 
analogy must be supplemented by corroborative testimony. Our pre- 
sent knowledge of the function of the spermatia of lichens rests almost 
wholly on the classical researches of Stahl 1 , on the reproduction in 
Collemaceae. In this group of lichens, according to Stahl, the sper- 
matia attach themselves to the tip of a trichogyne, at the base of which 
is a carpogonium. As the development of the carpogonium into the 
apothecium appears to follow the contact of the spermatia with the 
trichogyne, the spermatia may reasonably be assumed to be the fer- 
tilizing male element. Dr. Moeller does not think that this is con- 
clusively proved by Stahl. It is to be regretted that none of the 
species studied by Dr. Moeller belong to the Collemaceae , so that for 
this group we must still fall back on the researches of Stahl. 
With regard to the lichens of other groups, the present observations 
show conclusively that the spermatia are conidial in nature and not 
male bodies. In Buellia punctiformis , and in all the species of Ope~ 
grapha and Calicium above named, the spermatia produced hyphae 
which developed into thalli. A comparison of the results obtained by 
sowing the spores and the spermatia showed that there was no per- 
1 Ueber die geschlechtliche Fortpflanzung der Collemaceen. Leipzig, 1877. 
