XXxiv PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 
Scientific Committee, May 8, 1917. 
Mr. H. J. Elwes, F.R.S., V.M.H., in the Chair, with eight members 
present and Mr. R. Farrer (visitor). 
Primus spinosa forms. — Mr. J. Fraser, F.L.S., showed dried speci- 
mens of a number of forms of Prunus spinosa, including the variety 
macrocarpa, which he regarded as a hybrid between P. spinosa and 
P. communis. 
Narcissi.— Mr. Bowles showed flowers of the uncommon Narcissus 
dubius and the rare white form of N. muticus, which seems so difficult 
to grow and establish in this country. 
Various Plants. — Mr. Elwes showed Iris Wattii grown in a cold 
house, where, like /. fimbriata, it succeeds much better than outdoors, 
good growth being apparently necessary before a good flowering 
spike can be developed ; Fntillaria gracilis, which Mr. Bowles intro- 
duced from Montenegro ; Habranthus praUnsis ; Alpinia Elwesii, 
from Formosa ; Arundina bambusae/olia, from India, an Orchid 
rarely grown well now ; Rehmannia elatior and R. Henryi, both 
cold-house plants ; and Cymbidium devoniensis. 
Scientific Committee, May 22, 1917. 
Dr. A. B. Rendle, F.R.S., in the Chair, and eight members present. 
Gall on Rhododendron ferrugineum.—Mr. W. C. Worsdell, F.L.S., 
showed specimens of the well-known gall on Rhododendron jerrugineum, 
due to the attack of the fungus Exobasidium Rhododendri. This gall 
usually occurs on the leaves, but in one case on the plants shown 
it was on the corolla. 
Varieties of Pyrus Aria.— Mr. J. Fraser, F.L.S., showed specimens 
and commented upon the forms of Pyrus Aria which he had collected 
from wild sources in Surrey. Among them was one approaching 
the variety salicifolia, and another of the variety majestica. The 
latter is particularly interesting, for it is the form known as the Nepaul 
Service tree, or Pyrus Aria nepalensis (though it is not known to 
occur in Nepaul), and is generally assumed to have originated in 
nursery grounds. 
Alteration in foliage of Tr op aeolum.— Col. H. E. Rawson exhibited 
a plant of Tropaeolum tuberosum to show what he considered to be 
the sun's influence in causing the leaves to divide, as they normally 
do, into any number up to five lobes. He said 'The division has 
been observed taking place at critical altitudes of the sun, which 
confirmed previous years' observations. Prior to the leaf dividing, 
precipitation is seen to take place from the margin inwards, which 
indicated the exact vein affected. This precipitation, which is 
reversible, I associate with the starch of the tuberous plant 
considered to be a colloidal phenomenon." 
Tetramerous flowers of Narcissus.— From two sources came tetra- 
