756 Bachmann . — A New Type of Spermogonium and 
and an unusually long terminal cell. ( 4 ) The trichogyne grows towards and 
seeks out the male cells. In all other Lichens the spermatia are borne in 
large numbers in specialized organs, the spermogonia, and are extruded 
through the ostiole on the surface of the thallus, then to be carried by rain, 
dew, or possibly wind or insects, to the trichogyne, the tip of which is also 
above the surface of the thallus. If fertilization by means of water is more 
primitive, these then have more nearly retained or reverted to the aquatic 
habits of their ancestors in the production of large numbers of male cells 
and in the method by which the egg-cell is fertilized. 
The conditions found in Collema pidposnm have probably been 
developed with the land habit and approach those found in Pyronema 
and the Erysipheae. The greater activity of the trichogyne results in 
a certainty of fertilization which makes the production of a large number 
of male cells entirely unnecessary. There is here the same certainty of 
fertilization which exists in Pyronema , where there is usually but one and 
never more than two male cells for each female cell. The disappearance of 
large spermogonia is correlated with the certainty of fertilization and the 
diminished number of spermatia. It is plain, however, that this is not 
a reduced or vegetative fertilization in Blackman’s sense. The male cells 
are just as highly specialized as in other Lichens or the Red Algae. When- 
ever it has been possible to be certain of the manner in which the spermatia 
are borne, this has been found to be similar to that of other Collernas 
as well as of many other Lichens. The short, broad, faintly staining cells 
of the spermatiophores with delicate cross-walls are quite different in 
appearance from the elongated, easily stained cells with heavy septa of the 
vegetative hyphae. These spermatia are also similar to those borne in 
spermogonia in the apparent readiness with which they are separated 
from their place of origin. The limited ' size, the shape, the often con- 
stricted centre, the attraction for the trichogynes, and the fact that they 
are formed only at a particular stage in the life-history of the lichen, 
all show that they are specialized cells with a definite sex function. The 
trichogyne does not fuse with the vegetative hyphae, but seeks out these 
specialized cells exactly as in the case of all other sexual fusions. 
In view of what has been described of the relation of spermatia and 
trichogynes by Stahl, Sturgis, Lindau, Baur, and Darbishire, it would seem 
as if the sexual nature of spermatia could not be doubted. Still Fink (13), 
after noting Moller’s results in germinating spermatia, writes : ‘ This would 
seem to indicate that the spermatia, if they are sexual cells, have become 
so degenerate in certain Lichens as to lose their sexual function, becom- 
ing capable at the same time of reproducing vegetatively . 1 It seems very 
clear that the spermatia in my material are entirely homologous with 
those borne in the spermogonia of other Collernas, and it is impossible 
to conceive, after what has been described above of their behaviour in this 
