126 BOTANY. 
pastry, etc. (Mucor mucedo), is as follows: The vertical 
hyphe, which are filled with protoplasm, become enlarged 
at the top, and in each a transverse partition forms (A, a, 
Fig. 58), the portion above the partition () becomes larger, 
and, at the same time, the transverse partition arches up 
(B, a), finally appearing like an extension of the hypha, 
then called the columella (C, a). The protoplasm in the 
enlarged terminal cell (2) divides into a large number of 
minute masses, each of which surrounds itself with a cell- 
Fie, 58.—Diagrams showing mode of growth of the spore-case of Mucor mu- 
cedo. A, very young stage; B, somewhat later; C, spore-case with ripe spores. 
a in all the figures represents the partition-wall between the last cell of the fila- 
ment and the spore-case, b. 
wall; these little cells are the spores, and the large mother- 
cell is now a spore-case, or sporangium. 
266. The spores are set free in different ways: in some 
cases the wall of the spore-case is entirely absorbed by the 
time the spores are mature; in other cases only portions of 
the wall are absorbed, producing fissures of various kinds. 
The spores germinate readily when on or in a substance 
capable of nourishing them, by sending out one or two 
hyphe, which soon branch and give rise to a mycelium. 
Spores may, if kept dry, retain their vitality for months. 
267. Sexual reproduction takes place after the produc- 
tion of asexual spores. Two hypha, in the air or within 
