THE ORCHID REVIEW. 51 
infolded lobes dotted with chocolate-purple. The staminode is semilunar, 
notched above, pale whitish yellow, suffused with vinous purple and. reticu- 
lated with green. So far as I know this is the first hybrid in which the 
concolor blood has been carried into the second generation, and the 
quantity of that species shown in the present hybrid is marvellous. Several 
plants of it are in flower in the rich collection of Henry Graves, Esq., 
Orange, New Jersey. The name is given in compliment to his son. 
R. M. GRey. 
SPOT ON ORCHID LEAVES. 
Enquiries are frequently made respecting the cause of the disease of 
Orchids known as “ spot,” which disfigures the leaves and spoils their appear- 
ance, also the best remedy to apply, consequently a few notes on the subject 
will doubtless prove acceptable. That it is a disease of the tissues is well 
known, though its origin is not always so apparent. In some cases it is 
undoubtedly caused by microscopic parasitic fungi, but in others the tissues 
are seen in unhealthy condition without any trace of their presence. How 
far appearances can be relied upon in these cases is perhaps doubtful, as 
comparatively little is yet known upon the subject, and some have sought 
to account for the appearance of spot through the atmosphere being kept 
too moist and the house insufficiently ventilated, without reference to fungi 
at all. 
Disease on cultivated Orchids, however, may result from several different 
causes, one of which is the parasitic fungus known as Cladosporium Orchi- 
dearum, which attacks the leaves of Phalaenopsis and various other genera, 
sometimes doing much damage. It originates thus :—An excessively minute 
spore settles on the surface of a healthy leaf, and begins to germinate by 
pushing out a slender filament, called the mycelium, which enters the leaf 
through the stomata, or organs of transpiration, and runs about between the 
cells, completely disorganising them, though apparently not piercing their 
walls. As the intercellular spaces become filled with a mass of mycelia, 
the damage becomes apparent on the surface of the leaf in discoloured 
patches, which ultimately present a semi-rotten appearance. For some time 
the fungus grows entirely within the tissues of the leaf, but when it reaches 
maturity it again emerges, and produces fruiting tufts, or threads, which 
are sparingly branched, and bear pale olivaceous, usually septate spores, 
and these, of course, give rise to a new generation of fungi. 
The Vanilla disease, which recently proved so destructive in the 
Seychelles, is another parasitic fungus, known as Calospora Vanillz, 
which has, fortunately, not yet troubled us here, but it is well to be on 
our guard, for it is recorded to have been cultivated through all its 
