ON A PECULIAU FOKM OF MILDEW IN ONIONS. 91 



writers that the soil of some of them is not so fertile as the 

 appearance of the forests would lead the cultivator to expect. 

 This remark particularly applies to Sumatra, the forests of which 

 are supported in their luxuriance, in a great measure by the 

 moisture of the surrounding atmosphere." — p. 32. 



" Thunder and lightning are so very frequent as to be little 

 regarded by the inhabitants, though the former is more sonorous 

 and the latter more vivid than in Europe. — In all the quiet seas 

 of the East the lightning is very much dreaded by European 

 shipping. A heavy shower of rain is always preceded by light- 

 ning and thunder, and generally by strong wind." — p. 31. 



"Left early for Sebonyoh (Dec. 6). — One mountain near it 

 had had all its trees destroyed about twelve months since by a 

 fire, which had been ignited by the intensity of the sun's rays 

 on the rock beneath, and which had so dried the vegetation that it 

 spontaneously took fire, and the whole were destroyed. Notliing 

 but a succession of very wet summers can again restore it." — 

 p. 399. 



The custom of building the houses on tall posts to keep them 

 out of the water, sufficiently shows how formidable the floods 

 must be in Borneo, and how damp such an atmosphere must be 

 under a temperature of 85^. 



XV. — On a peculiar foi-ni of 3Iilderv iti Onions. By the Rev. 

 M. J. Berkeley, M.A., F.L.S. 



Few crops more frequently disappoint the exioectations of the 

 cultivator than onions. Wet and dry seasons are alike injurious, 

 and there are few years in which they do not suffer more or less 

 from mildew ; and this not merely under a bad system of culti- 

 vation or in indifferent soil, for highly mildewed crops occur in 

 the most favourable situations, and where the management of 

 them is best understood. The fields at Sandy, in Bedfordshire, 

 where perhaps the best onions in England are grown, are ex- 

 tremely subject to mildew, as can scarcely have escaped the 

 notice of any one who has been in the habit of travelling year 

 after year along the road from St. Neot's to London. Neither 

 is the mildew of one kind only, or confined to one particular or- 

 gan or portion of the plant. Whole beds are destroyed in an 

 early stage of growth by a parasitic fungus which attacks the 

 leaves, and is nearly allied to Botrytis infestans., but which, in- 

 stead of being white, is of a pale reddish grey, with spores far 

 more elongated, and flocci quite destitute of the nodules which 

 are so characteristic of tiie potato mould. Sometimes the crop 

 seems for a time to be healthy, but gradually, after the formation 



