16 Ver Brecuer Wirrrock. 
are far from rare, especially i the principal filament. Here it does 
not seldom happen, especially in specimens that are but half-fertile, that 
the formation of spores takes place even quite acropetally (pl. 2, fig. 7). 
Rules as to the order of the formation of spores which have, as it has 
seemed to me, no exception, are 1:o That the top spore has, at least 
in shorter branches, been developed before all the mclosed spores of 
the branch, and 2:0 That the spore which is developed by the support- 
ing cell of the branch Gf such a spore be developed, which is not al- 
ways the case), is formed later than all the spores in the supported 
branch. — Although the material of the other species of Pithophora which 
I have had to examine has not in general given me opportunities to 
make observations on the order of the spore formation, still I have 
now and then succeeded in making an observation on this head. Thus, 
it is distinctly seen in the specimen of P. wqualis nob. which I have 
represented pl. 1, fig. 5, that here the formation of spores takes place, 
‘upon the whole, in a basipetal direction, even if the second spore from 
above be developed somewhat later than the third. 
As has been mentioned above, the formation of spores belongs, 
as a rule, to the cauloid part of the thallus. As exception spores may, 
however, be formed also in the rhizoid part at least of P. kewensis nob. 
(pl. 4, fig. 9—11), P. Cleveana nob. (pl. 4, fig. 14, 18) and P. polymorpha 
nob. (pl. 4, fig. 19). In P. kewensis nob. I have even found rhizoids 
with as much as three spores (pl. 4, fig. 11). The formation of spores 
in the rhizoid takes place in exactly the same manner as in the cauloid, 
only with the difference necessitated: by the different direction of the 
increase, so that the spore is here formed not in the upper, but in the 
lower part of the mother cell. 
As to the time of the spore formation it is, judging from the ° 
observations on this head that I have had access to, very different in 
different species. In P. kewensis nob. I have seen the formation of 
spores take place in the months of July and August. Of P. @qualis 
nob. I have fertile specimens, also collected in July. P. Cleveana nob. 
and P. Zelleri (v. Mart.) nob. are found with spores in October, P. 
Roettleri (Roth) nob. in January and P. swmatrana (v. Mart.) nob. in 
March. (At what time the formation of spores takes place in P. poly- 
morpha nob. is quite unknown to me). However, it may be probable 
that the formation of spores takes place during longer periods of the 
year than those which have been indicated above for the different 
species, 
sal 
