315 
large and well developed asci are formed, but which fail to pro- 
duce any spores. 
The next and possibly most important question discussed is 
that of sexuality. It may be noticed here in passing, that with- 
out question, the belief that this feature occurs in any class of 
lichens, and in fact, in any of the higher fungi, is slowly losing 
ground. The adherents of this theory have been obliged to 
retreat from group to group, till they reached the Floridez, or 
red sea-algze, where the proofs of sex are still considered con- 
clusive. 
Krabbe says there is no possibility of sexuality in the genus 
Cladonia, that is to say, no possibility of fertilization accomplished 
in any manner with which we are acquainted. The only indi- 
cation which might in any way imply such an act, he describes as 
follows: In some instances the ascus-hyphe, when fully grown 
and swollen out, forming large cells, apparently for the develop- 
ment of spores within, lose their character as ascus-hyphe, and 
turn back to sterile ones. This is brought about by the apical 
portion of the cell changing its manner of growth, becoming 
smaller in diameter, and stretching up until it somewhat resembles 
a trichogyn, and the enlarged part at the base resembles an 
ascogon. Now he says of this, the resemblance to the real 
ascogon and trichogyn of the Floridez is very slight, and there 
are always two points of difference, these are the thread or tubular 
cell resembling the trichogyn, may branch, and it always starts 
gradually from that part which rasembles the ascogon. In both 
respects this is unlike the development of the true ascogon. It is 
hardly possible for those accustomed to the teachings of the text- 
books on general botany, and to the plates with the forked 
trichogyn of the Collemacee, taken from Stahl’s work, sal pass 
over this so lightly. The question will recur, what end is to be 
Served by such a change of an organ. 
The explanation of a certain element of the ce eet 
a very striking feature of this most interesting article ; . scp 
the presence of large numbers of soredia about the outer .. 
ference of the podetia. The older writers on lichens regard se 
Soredia as formed on this organ in the ordinary way by fa 
this means of vegetative reproduction is accomplished. In short 
podetium forms 
