616 Microscopical Fungi Infesting our Cercals. [October, 
are generally known under the name of rusts and brands, or 
Uredinee. 
In examining our corn-fields in the beginning of summer we 
shall most likely find a number of plants covered all over with 
bright rusty, later in the year with dark brownish spots and lines. 
These pustules are produced by parasitic fungi which have their 
seat under the epidermis of the infected plants, and after being 
developed, burst through the epidermis in order to disseminate 
their spores. The very interesting development of these Ure- 
dinez is a comparatively recent discovery, the more interesting 
as the originators of the disease are to be found on plants belong- 
ing to families entirely different from those in which the parasites 
are developed. 
If in May or June we examine the leaves of some Berberide@, . 
Rhamnacee or Asperifoliacee growing in the neighborhood of 
our corn-fields (particularly those in damp localities), we may be 
pretty sure to find the under surface of such leaves covered all 
over with little cup- or jar-like bodies of a bright-rusty color. 
These little cups are what have long since been known as cluster- 
cups, or Æcidium. They present an elegant object under the mi- , 
croscope, and delicate sections will show that the interior of the 
cups is crowded with basidia, from which regular rows of bright- 
colored spores proceed. (These cluster-cups are generally 
attended by numbers of those strange little bodies known as 
spermogonia, growing mostly from out of the opposite side of 
the leaf, and sending forth thread-like spermatia, the real nature 
of which has as yet not been ascertained.) 
Prof. de Bary, of Strasburg, has been the first to show that 
when these Æcidium spores are brought on certain species of 
corn, for instance those of Berberis, or Barberry, on rye, they 
immediately begin to germinate. The tender germ tubes force 
their way through the stomata and rapidly develop within the 
infected leaf a’'mycelium from which the afore-mentioned spores 
are produced on basidia beneath the epidermis. Prof. de Bary 
was led to the investigation by the pertinacious and often ridiculed 
assertion of old farmers, that the shrubs of Barberry were inju- 
rious to rye and oats; and indeed, his repeated direct experiments, 
as well as those of a number of other botanists, have proved 
beyond doubt that a very dangerous form of rust, the Uredo 
linearis, is produced only by the spores of Barberry cluster-cups — 
