19G 
stalk and sometimes the ear of the corn plants will probably be 
covered with the black lines of tlie Puccinia. During dry seasons 
the Dust develops but slowly, and is often confined to the leaves of 
the corn, where it causes comparatively little mischief ; if, however, 
the Puccinia is largely develoj)ed, then very serious damage ensues 
to the crop. 
Another curious fact is, that if in spring time the spores of a 
certain Puccinia are dusted on the under-side of the leaves of the 
Larberry, these sirores nray germinate, and, oir the mycelium thus 
formed smaller spores, called sporidia, rvill shortly be produced ; 
these latter will in their turn germinate, and form a mycelium 
which penetrates the epidermis of the leaf, and gives rise to the 
PEciclium of Avhich I spoke just now. This development of a 
iiurgus on one plant from tire spores of a fungus growing on 
some other plant has been the subject of many exjreriments, 
especially by the Continental Mycologists, De Bary, Magnus, 
Wolff, and the brothers Tulasne. Here a wide field lies ojren for 
observation and experiment, and it seems not improbable that 
most, if not all the species of Uredo, Trichohasis, Lceythea, &c., 
will be found to be only early stages of some Puccinia, or other 
more highly developed fungus. 
In the summer of this year I Avrote to ask ]\I. Maxime Cornu, 
of the Musce Botamque, in Paris, how he had succeeded in the 
experiments Avhich I Icucaa’’ he Avas making on this subject. Ho 
told me that on May 18th, and again on June 4th, he soAA'ed spores 
of jEcidvujm rliamni (taken, as the name implies, from the Buck- 
thorn) on young Oat plants, and that on June 11th and July 10th 
respectively, he perceived some pustules of Trichohasis mhigo vera, 
Avhich is the early stage of Puccinia coronatcu Similarly, the 
spores of Peridermium inni, soAvn on Groundsel, produced Coheo- 
spormm senecionis ; those of Peridermium elatinum produced 
Puccinia rhododendri • and those of JEcidium urticce (so common 
during the past summer on our Nettles) produced Puccinia 
caricis on the loaves of Carex liirta. These arc most A^aluablo 
facts. 
As to the relation between tlie Adcidium of the Barberry, and 
tlie MddeAv of the Wlieat {Puccinia graminis), M. Maximo Cornu 
referred me to the following interesting account from tlie ‘Deports of 
the Botanical Society of France’ for the years 18G8— G9. An 
