THE FUNGI 



547 



[Chap. XLIV 



During growth and multiplication, a small outgrowth ( "bud" ) appears 

 at the side or end of a cell. This increases in size and finally separates 

 from the parent cell as a new yeast plant. This process is repeated in- 

 definitely in favorable moisture, food, and temperature conditions. This 



Fig. 238. Diagrammatic representation of zygotes formed in tlie water mold, 

 Achlija, when liyphae of a female mycelium (left) come in contact with those of 

 a male mycelium (right). The numerous small branching hyphae around the 

 periphery of the male mycelium are antheridial branches on which the male 

 organs (antheridia) containing male nuclei develop. The scattered small darkened 

 spheres on the female mycelium represent immature egg cases (oogonial initials). 

 The darkened awl-shaped hyphae and spherical masses of spores at the apexes of 

 certain hyphae in both mycelia are vegetative propagules. For further details of 

 the sexual processes, see Fig. 239. From ]. R. Raper. 



mode of vegetative multiplication is known as "budding." Some yeasts 

 have simple cell division only. Under some conditions the cells do not 

 separate immediately, but form fragile bead-like chains that are more 

 or less branched (Fig. 237). Under other conditions the contents of the 

 yeast cell may divide internally into 2, 4, or 8 separate protoplasts, and 

 these round up as spores, capable of a relatively long period of dormancy. 

 Water molds. In temperate latitudes in early spring dead fish and 

 other aquatic animals may be found in ponds and streams, completely 

 covered with a colorless slimy mass of fungous hyphae. The same 



