October 19, 1882. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 369 
A few centuries ago the true nature of the Wheat disease was 
unknown ; some persons attributed it to the bitings of minute 
poisonous insects, others to some baneful influence carried by the 
wind. It was not till 1767 that the blight was proved to be 
caused by a mildew or parasitic fungus. In 1799 our English 
botanist, Sowerby, illustrated the Wheat Mildew in “ English 
Fungi,” plate 140. At the very time that Wheat blight was shown 
to be of fungus origin, English farmers were most stoutly assert¬ 
ing that Wheat blight was always more virulent in the neighbour¬ 
hood of Barberry bushes. 
Against the connection of the Barberry and Wheat fungi it was 
reasonably urged that Wheat Mildew was quite as destructive in 
New Zealand and Australia as in Europe, whilst in the first- 
mentioned places there are no native Barberries to cause the 
blight. Moreover, it was urged that Barberry bushes were so rare 
in this country in comparison with the commonness of Wheat 
and its mildew, that under any circumstances it would be utterly 
impossible for Barberry bushes to produce sufficient baneful 
influence to infect all the corn. It was now soon observed that 
Barberry leaves were afflicted with a yellowish fungus not unlike 
the early state of Corn mildew, but botanists asserted that the 
fungus of the Barberry and the fungus of the Wheat were totally 
different in structure and nature. Many of our best botanists 
have kept to this opinion till quite lately, and it is indeed possible 
many may still adhere to the opinion that the Barberry and 
Wheat fungi have no connection with each other. Sir Joseph 
Banks, President of the Royal Society in 1805, however, was the 
first botanist to point out the true nature of the ailment of corn, 
and in a paper on Wheat Mildew, published in the “ Annals of 
Fig. 60.—Fungus of Barberry. 
Agriculture,” vol. 43, he gave in his adhesion to the views of the 
farmers. Sir Joseph Banks, after an examination of the parasite 
and all the evidence on both sides, printed his conviction that the 
fungi of the two plants were possibly the same species, and that 
the Barberry blight was probably transferred to the corn. At 
length Professor De Bary gave some confirmation to Sir Joseph 
Banks’ views by stating that he had caused Wheat Mildew to 
appear artificially from infection from the fungus of the Barberry ; 
but as De Bary failed to infect the Barberry back again from the 
corn fungus, and as other botanists could proceed no further, if 
indeed so far, the question stood in abeyance. One set of men 
thought the evidence sufficient, and sided with the farmers and 
Sir Joseph Banks, whilst other men were unconvinced, and were 
always asking for further and better evidence. No better evidence 
was, however, forthcoming till Mr. C. B. Plowright, surgeon, of 
King’s Lynn, last year made a series of experiments which were 
at first laid before the Woolhope Club at Hereford, and more 
recently, with many new experiments, published in the “ Gardeners’ 
Chronicle.” Mr. Plowright states that he has really gone a step 
further than other botanists, and produced the Barberry blight 
from infected Wheat. Some botanists may indeed reply that the 
fungoid diseases of the Barberry are so extremely few that, if the 
plant has any ailment at all, it is pretty sure to be the one under 
discussion, and that the Barberry leaves experimented upon would 
possibly have had the disease if left alone, or if brought into 
contact with any other organic or non-organic material. 
In the light of Mr. Plowright’s recent careful experiments, we 
will take the views first advanced by Sir Joseph Banks as now 
proved, that the fungus of the Barberry really is one potent cause 
of Corn Mildew. We propose to illustrate the entire subject, and 
may at once say that all our illustrations are taken direct from 
Nature and engraved to scale. 
For convenience we will begin with the Barberry (Berberis vul¬ 
garis), a plant which is probably well known to all our readers. 
A group of three of its leaves, armed with thorns at the base, is 
illustrated at A (fig. 60). The leaves at B, b show their under sur¬ 
face to the spectator, and on this under surface is seen growing 
the Barberry fungus (iEcidium Berberidis). It grows in yellowish 
patches, and when these patches are carefully observed or slightly 
magnified they will appear as companies of minute yellow cups. 
C represents the upper surface of a Barberry leaf, and on this upper 
surface there are frequent companies of extremely minute black 
dots, as illustrated. These companies of black dots on the upper 
surface frequently correspond in position with the yellow cups on 
the under surface; and although the latter were at one time sup¬ 
posed to be fungi perfectly distinct from those on the upper surface, 
they are now known to be the same, for they spring from the same 
spawn inside the leaf. This tuft of leaves with its fungi is natural 
size. If we magnify the cups on the under surface of the Barberry 
leaf with a glass magnifying twenty diameters we shall see them 
as yellow cups or inverted open-mouthed bells, as at d. A much 
higher power, however, is required to understand these fungus 
cups. So if we cut the Barberry leaf in two across a group of cups 
and magnify fifty diameters we shall see them as at E, F. E re¬ 
presents the outside of a cup, and we now perceive it to be filled 
with yellow dust, which flies out like beautiful rows of beads in 
necklace fashion. At F we have fortunately cut right through the 
middle of a cup, and we now not only see the internal mass of 
bead-like seeds, but we see that the cup itself is built up of a mass 
of similar minute circular bladders packed closely side by side so 
as to make an enclosing skin. Underneath this illustration at G 
are three of the little black specks (termed Spermagonia by bota¬ 
nists) peculiar to the top of the leaf. These specks are now seen 
in section. They are minute flasks embedded in the leaf. Their 
mouths are like exquisitely fine bundles of threads or rods, and 
carried on and round these rods are numerous atoms of the 
finest conceivable dust as illustrated, h, h shows the thickness of 
the Barberry leaf, also enlarged fifty diameters. The round 
bead-like bodies seen flying out of the cups are spores, seeds, or 
ovules. The extremely fine dust round the rods at G are pro¬ 
bably of the nature of pollen, as their name (spermatia) imports. 
If we now desire to thoroughly understand the nature of Corn 
Mildew we must learn all about the spores and spermatia, and 
a much higher magnifying power becomes necessary. If we 
examine the seeds or spores with a power giving six hundred 
diameters we shall see them as golden spheres as at J (fig. 61), 
dotted round the circumference with the little transparent 
granules derived from the black flasks at G. When ripe the 
spores readily germinate, and the first sign of germination is six 
slight protuberances from the sphere, one at each pole and four 
round the equator. Sometimes a thread is protruded from all 
the six positions, but it commonly happens that one thread 
only is protruded. This thread winds in a convolute fashion as 
at K, and the whole contents of the spore or seed is poured into 
the end of the tube as at L. The life of the fungus upon the 
Barberry here ends. At first we have seen it as a capsule or 
bell full of seeds living at the expense of the Barberry leaf; we 
have then seen its seeds fertilised by the minute granules attached 
at J ; and lastly observed their germination. 
The older botanists considered that these germinating seeds or 
spores reproduced the Alcidium fungus on other Barberries, but 
the newer school maintains that the flEcidium spores are in¬ 
capable of reproducing the iEcidium direct upon other Barberries. 
It is confessed that they will germinate upon Barberry leaves, as, 
indeed, they will upon almost anything in damp air, but it is 
asserted that they speedily perish, and are positively powerless 
to directly reproduce the iEcidium. The newer school also 
maintains that when these AScidiutn spores are placed on the 
leaves and other parts of Wheat and various Grasses they 
germinate with extraordinary vigour, and produce the fungus of 
Corn Mildew. The evidence in this direction we will now 
examine. 
A less high power of the microscope is again sufficient, and at 
M an extremely small piece of the skin taken from the under side 
of a leaf of Wheat is represented magnified two hundred diameters ; 
at N, N, are two seeds from the Barberry fungus, both germinating 
and sending their growing points into the substance of the Wheat 
leaf through the organs of transpiration of the Wheat plant seen 
at o, o ; the dotted lines at p, p, show the growing points of the 
