178 
Journal of Mycology 
[Vol. 10 
tions need be here given. For example, the common Black Mould, 
or Mucor, besides producing conidial spores is sometimes seen 
FIG. 12 . 
Fig. 12. Ulothrix zonata, a common fresh-water Alga, attached by a rhizoid (r ), pro¬ 
ducing zoospores. The large swarm spores (sw. sp.) have four cilia. The smaller 
swarm spores have two cilia; in some cases they are gametes (g.) z. <?. fuse to forma 
zygospore (z.). The zygospore may in turn produce swarm spores which grow into the 
usual form of the species; or the zygospore may develop, as many swarm spores do, 
directly into a plant like the ordinary filamentous form (Ul. zo.). 
to produce sexual spores as follows. Two more or less differen¬ 
tiated hyphae give rise by the stimulus of contact to swollen 
portions each of which near the point of contact forms a septum 
Fig. 13. Zygospore formation in the Mucor, or common Black Mould An early 
stage of the gametophores is shown at a ; the cells are becoming enlarged at b, and at c 
the gametes are formed ; fusion is shown at d, and the mature zygospore is represented 
at e. 
thus producing the two gametes. The common wall of these co¬ 
hering cells becomes absorbed and the contents fuse into one mass 
and thus a single spore, i. e., a sexual spore, is formed (Fig. 13). 
