42 THE ORCHID REVIEW.  {Marcu-Aprit, 1919. 
and its parents.”-- Unfortunately, it carries the question no further, and I 
find no record of the earlier meeting when the seedling was exhibited. Can 
anyone trace a drawing of Mr. Burnley Hume’s original plant ? 
In searching the records we have discovered what we believe to be am 
earlier appearance of this hybrid. In 1847, areputed O. cordatum appeared 
in the collection of S. Rucker, Esq., of which a coloured plate appeared 
(Paxt. Mag. Bot., xiii. p. 147). It is not that species, and it has since been 
referred to O. maculatum, but with this also its characters are at variance. 
It has more of the O. Rossii shape, but the colour is light greenish yellow, 
with light brown markings, and from the combination of characters we 
believe that it must be referred to O. Humeanum, which is known to vary 
considerably. It probably appeared as an imported plant, but no dried 
specimen can be traced. R. A. ROLFE. 
aa LEAF SPOT OF ORCHIDS. laces 
N article on Leaf Spot in Orchids, by Mr. W. B. Brierley, has just appeared 
(Gard. Chron., 1919, i.p. 61). It isremarked that “Orchid Spot” is 
not a single and specific disease, but a congeries of diseases, all little under- 
stood, and urgently in need of detailed investigation. The one to which 
the term is most commonly applied, consists of pale straw-coloured spots, of 
irregular shape, on the upper surface of the leaves, which ultimately become 
brown and shrivel. This is the result of chilling the leaves below their 
power of resistance, and is generally caused by the drip of condensed water 
from the cool glass roof. It is not due to the attack of a parasitic fungus, 
and hence, cannot be checked by antiseptic solutions. The obvious, but 
only remedy, is to remove the cause of the mischief. 
_A second form of spot is prevalent in the neighbourhood of large towns, 
and this is believed to be chiefly due to atmospheric pollution, many Orchids 
being peculiarly susceptible to the presence in the atmosphere of minute 
quantities of deleterious substances. This, like the preceding, appears to be 
common to all the more usually grown species of Orchids. 
Certain other forms of spot are caused by parasitic fungi, as Hypodermium 
Orchidearum on Cymbidium eburneum, by a Cladosporium, possibly C. 
Orchidis, or the’ubiquitous C. herbarum, and by Botrytis cinerea. In such 
cases, sponging or spraying with a 3 to 4 per cent solution of calcium 
bisulphate is recommended, accompanied by the most rigorous cleanliness, 
and the immediate removal and destruction by burning of every fragment of 
diseased material. 
There are other forms of spot which have been found on various Orchid 
leaves, the cause of which is at present’ imperfectly known, though it is 
