146 BOTANY. 
fungus which protrude through the epidermis of the host. 
In the Mildews (species of Peronospora) these branches 
Fie. 66.—Showing tips of two conidia-bearing branches of Potato-mildew 
(Peronospora infestans). Highly magnified. 
find their way through the breathing-pores, and bear their 
“spores singly upon lateral branchlets (Fig. 66); in the 
White Rusts (species of Cystopus) the 
conidia-bearing branches collect under the 
epidermis and rupture it. Here the coni- 
dia are borne in chains or bead-like rows 
(Fig. 67). 
292. In some species the conidia germi- 
nate by forming a tube; in others they 
divide internally and finally emit many 
zoospores. The latter eventually protrude 
/ a tube and bore their way into the cells of 
Fie. 67,—Showing the host (Fig. 68, a to 2). 
the tips of three coni- . 
_dia-bearing branches 293. The sexual reproduction always 
of the White Rust of a . 
Peppergrass. Magni- takes place in the intercellular spaces of 
a imes. AG 
the host. Lateral branches of two kinds 
appear upon the hyphx; those of one kind (the young 
