474 THE COTTAGE GARDENER AND COUNTRY GENTLEMAN’S COMPANION.—September 30, 1850. 
ONCIDIUM PINELLIANUM. 
(Pirelli's Oncid.) 
This is a very beautiful Brazilian species, 
of which no account appears to have yet 
been given publicly. The name, which is 
of foreign origin, occurs in Messrs. Lod- 
diges’ catalogue, where it is said to have 
been introduced in 1841, but I do not find 
it elsewhere. The flowers are a very bright 
yellow, with dark-brown blotches and spots 
on the sepals, petals, and base of the lip: 
in the amount of blotching there is, how¬ 
ever, some variation in different individuals. 
They appear closely packed in a secund 
manner upon the short branches of a 
small panicle, as is shown in the cut, 
where 1 represents the column and wings 
magnified, and 2, a magnified flower from 
which the columns and upper half of the 
lip have been removed. The species is 
very near O. spilopterum (also called O. 
gallopavimim), from which it differs in 
having a branched panicle, sepals, and 
petals larger in proportion to the lip, and 
a crest more broken up at the base into 
short parallel plates. I am not sufficiently 
acquainted with the plant to speak of it 
further.—J. L. — (Horticultural Society's 
Journal. 
ON A FORM OF SCAB IN 
POTATOES. 
By the Rev. M. J. Berkeley, M.A., E.L.S. 
There are two very different diseases 
known commonly under the name of scab, 
of which one is far more general than the 
other, but, at the same time, less injurious 
to tbe intrinsic value of the tubers, 
though, in point of fact, reducing their 
market value in consequence of the rough 
pocky aspect which it produces. 
The first, of which it is now my inten¬ 
tion to treat, was described and figured by 
Martius (Die Kartoffel-Epidemie, p. 23, 
tab. 2, figs. 9-13; tab. 3, figs. 36-3^), and 
is characterised by the presence of an 
olive-green or brownish pulverulent Hy- 
pliomycete (Tuburcinia Scabies, Berk., 
Journ. Hort. Soc. Bond., vol. i. p. 33, tab. 
4, figs. 30, 31), which gives a very peculiar 
appearance to the pustules, and to which, indeed, it is not 
confined, but occasionally forms a stratum a line or more in 
thickness beneath the greater portion of the cuticle. A few 
scattered tubers occur now and then affected by this disease, 
but it is very rarely so prevalent as to draw much attention. 
The Potato crops, however, suffered greatly from its ravages 
in the Scilly Islands and in Cornwall during the present 
summer, where it appeared under a very destructive form. 
Mature specimens were forwarded to me, with the promise 
at some future period of a supply of tubers in every stage 
of the disease. I was, however, disappointed in my hope 
of being enabled to investigate its nature more closely, 
possibly because the malady, as Martins reports, is several 
weeks in going through its phases. Indeed, it should seem 
that, in Germany, it does not usually occur till after the 
tubers have been raised for pitting; and as it first appears 
under the form of discoloured spots, which gradually spread 
and become confluent, and of which the cuticle is not at 
all ruptured for some weeks, it has been supposed by the 
German peasants to arise from injuries received by the 
tubers in the course of harvesting. This notion seems, 
j however, to be completely contradicted by the fact of its 
occurring to a considerable exteut on the tubers in situ. 
The second disease, which passes, though perfectly dis¬ 
tinct, under the name of scab, is extremely common in 
Oncidium Pinellianum. 
newly turned-up soil, especially if it contains cinder-dust or 
lime-rubbish, or where these form a considerable part of 
the manure in old tilths, for it is by no means confined to 
new ground, but is to be found in a greater or less pro¬ 
portion in most crops, in some instances every individual 
tuber being attacked, in others the scabby tubers making 
the exception to the smooth and healthy appearance of the 
sample. 
It commences at a very early stage in the growth of the 
tubers, whether in those produced immediately from the 
sets or those which often make their appearance with the 
first heavy rain after a long-continued drought. I have 
seen during the present autumn Potatoes already attacked 
which did not exceed a quarter of an inch in diameter, and 
it is on these young tubers only that the early stage of the 
disease can be studied. Its first appearance is that of a 
minute brown speck, paler on the edge, and staining the 
subjacent cells of the cuticle, which, as is well known, 
consists of a variable number of layers of muriform tissue, 
and which should seem rather to be considered as the outer 
portion of the bark of the underground stem than as of the 
nature of epidermis. It is, therefore, only in a popular 
I sense that it is here termed cuticle. The discolouration 
• does not proceed beyond the cuticular cells, nor is the 
cuticle at all thickened, but is occasionally more or less 
