140 



BOTANY. 



fungus which protrude through the epidermis of the host. 

 In the Mildews (species of Peronospora) these branches 



Fig. 66.— Showing tips of two conidia-beaiing 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 



Fib. 67.— Showing the host (Fig. 68, a to i). 

 the tips of three com- ^tm. i t • , 



1 1 ia-hearing branches iyd. Jine sexuai reproduction alwavs 



iif the White Rust of , . . ■' 



I'eppergrass. Magni- takes place m the intercellular spaces of 



fled 400 times. i, i_ t 



the host. Lateral branches of two kinds 

 appear upon the hyphae; those of one kind (the young 



