NOMAD FUNGI 
49 
NOMAD FUNCtI : THE EECLASSIFICATION OF THE 
UEEDTNE^. 
BY W. B. GKOVE, B.A., HON. SEC. OF THE BIRMINGHAM NATURAL 
HISTORY AND MICROSCOPICAL SOCIETY. 
< Continued from page 31. < 
Life-History of a Hetercecious Species. 
It will illustrate this important phenomenon of heteroecism, as well 
as confirm the whole theory, if I trace the annual cycle of Puccinia 
(iraminis through its various forms; for, if it is once proved that P. 
f/raniinis is descended from CEcidiwn berberidis, no one can any longer 
conceive a doubt about the truth of the theory in the other or mitcsciovs 
species, where the various forms appear on the same plant. 
This Puccinia (viz., (jraminU), then, begins its life in spring as an 
(Ecidium, or cluster-cup, on the leaves of Berberis, usually upon 
Berbent vulgaris, the common wild barberry, but also upon most of 
the cultivated forms. If the spores of this, when ripe, be taken and 
sown upon the leaves of a young wheat plant, which has never been 
exposed to the risk of any accidental infection by other spores, it 
germinates, throwing out a germ-tube. This germ-tube travels over 
the leaf, searching for a stomate into which it may enter. As it 
elongates it assumes a spiral form. Sometimes after making four or 
five turns from left to right, it will reverse its motion, and make the 
succeeding turns from right to left. It is obvious that by these means 
it adds greatly to its chance of finding and entering a stomate ; in fact, 
this motion, and the object of it, are very similar to that which Dr. 
Darwin has so recently made known with reference to the growing 
radicle of flowering plants. Mr. C. B. Plowright, to whose experiments 
I am now referring, says that all the trouble he took in conducting his 
experiments was fully repaid by the intense pleasure of watching this 
germ-tube feeling its way over the epidermis of the wheat-leaf in 
search of the opening by which alone it could enter in. Having 
obtained an entrance, the tube, by repeated branching, forms a myce¬ 
lium, which increases within the plant tissues, and at last the ends of 
References to Plate IV. 
Pig. l.—a, Section of two cups of CEcidium grossularice, showing the spores 
originating in chains beneath the epidermis, X 88; b, three spores, X 360—(from 
natui'e). 
Fig. 2.—Two uredo-spores of Puccinia graminis, seated on their pedicels, or 
basidia, X about 500—! after De Bary). 
Fig. 3.—Group of teleuto-spores of Puccinia graminis, X 250—(from nature'. 
Fig. 4.— Germinating spore of QUcidiuni tussilaginis, X about 240—(after 
Plowright). 
Pig. 5.—Germinating teleuto-spore of Puccinia magmcsiana; each segment of 
the spore has thrown out a germ-tube, bearing three “ sporidia,” X about 400 
— after Plowright'. 
Fig. 6—Sperrnogone of QUcidiimi tussilaginis, emitting a tendril of minute 
spermatia in water, X 240—(from nature). 
