ON THE EFFECTS OF URBAN FOG UPON CULTIVATED PLANTS. 139 



large and full, of a dull cloudy-white, rather acid. A profuse 

 cropper. A very distinct variety. 



Shilling's Queen. — See Cut-leaved White. 



Transparent White. — See Common White. 



5. White Dutch (syns. Blanche d'Hollande, Blanche 

 d'Anglctcrre). — Plant of moderate vigour, compact ; leaves large, 

 flat, deep green, with a narrow yellow margin ; bunch medium 

 size; berries large, clear white, sweetly flavoured. Free cropper 

 and an excellent sort. 



6. White Imperial (syn. Blanche de Boulogne, Blanche 

 Impcrialc). — Plant moderately robust ; bunches long ; berries 

 medium. 



Wliite Transparent. — See Common White. 

 WilmoVs Large White. — See Cut-leaved White. 



ON THE EFFECTS OF UEBAN FOG UPON 

 CULTIVATED PLANTS. 



Preliminary Beport by Professor F. W. Oliver, D.Sc, F.L.S., 



presented to the Scientific Committee of the Boyal 

 Horticultural Society, March 24th, 1891. 



The investigation, as to which I am now drawing up an interim 

 report, has been undertaken by the Royal Horticultural Society's 

 Scientific Committee, supported by a grant from the Eoyal 

 Society to meet the cost of apparatus, &c. The question of the 

 effects of urban fog on plant life has come prominently before 

 our town and suburban cultivators, and the 'damage from this 

 cause, which may formerly have been regarded as exceptional, is 

 now admitted to be chronic and constitutes an ever-increasing 

 source of dismay to all interested in horticulture. The action of 

 the Scientific Committee in taking up this question is but the 

 reflection of a general feeling amongst cultivators that something 

 ought to be done. A winter never passes now without one or 

 more prolonged spells of fog, contaminated with the products of 

 coal combustion. For weeks at a time, during the winter, the 

 London suburbs are enshrouded in semi- darkness, whilst the air 

 is tainted with foreign and offensive matter. Coincidently, there 

 occurs a dropping of buds, a destruction of flowers, and, what is 



