ox WHITE RUST. 51 



seen so much injury arise from a little production analogous at 

 least if not in reality very closely related, which at a certain 

 definite time made its appearance in a particular garden at 

 Margate, and from thence spreading over the greater part of 

 Europe or even beyond its limits, that we are not in a position to 

 judge of the possible importance of any parasite, merely from the 

 effects produced during the first season in which it may be 

 observed. The whole question of the production and appearance 

 of these organisms is involved in mystery, but though we are 

 unable to come to any general conclusions now, it is quite possible 

 that the simple record of facts like the present may not be with- 

 out its weight at some futui'e day. The fungus may be recorded 

 as follows. 



OkUum hnllatum. Berk. & Br. Mss. soris punctiformibus 

 demum confluentibus epidermide primum vestitis ; sporis ovatis 

 ellipticisque minutis subgelatinosis. 



The figure represents at (a) a group of the spores, either simple 

 or more or less compound ; and at (b) some of the cells of the 

 leaf in which the endochrome is converted into distinct hyaline 

 vesicles. 



i^rA^i^ 



Oidium buUatum, Berk. S,- Br. — White Rust on Peav Trees. 



E 2 



