F. T. Brooks and M. A. Bailev 1 97 



of Wisley informed one of us in 1913 that he had seen "a piece of a 

 Lonicera (? japonica) with foliage showing all the characteristics of 

 silver-leaf." 



In 1914 one of us saw a single elm leaf on a small branch arising 

 about seven feet up the trunk of a large tree, the middle of which was 

 markedly silvered with the exception of some dark green flecks although 

 the margin was either dark green or white. Other leaves of the same 

 branch showed variegation but not silvering. 



Finally, a few other leaf conditions may be noted, which, though 

 not silver-leaf in the sense described above, simulate it closely. 



While one of us was in Malaya during 1914 a branch of the Borneo 

 camphor tree {Dryohalnnopa aromntira) came under observation which 

 appeared as if silvered. The foliage of this plant is normally dark green 

 but this branch had been severed from the tree and had been lying 

 exposed to the sun for c few hours, after which the foliage appeared 

 to be silvery. The leaves of the plant are too stiff to wilt and it seemed 

 as if the upper epidermis had broken away from the mesophyll, thus 

 allowing air to accumulate below the epidermis and so altering the 

 character of the reflected light. 



In the Journal of the Board of Agriculture for 1913 one of us(3) 

 recorded the occurrence in the south of France of several kinds of 

 shrubby plants, notably Arbutus unedo, Myrtus communis, Viburnum 

 Tinus, with "silvery'" foliage in contrast to the dark green leaves which 

 these plants usually possess. Large numbers of these "silvery" plants 

 were seen in irregular groupings, and on casual examination one would 

 have certainly declared that these plants were silvered. Careful observa- 

 tion of leave;; in an intermediate condition showed, however, that the 

 "silvery" appearance was due to innumerable punctures of the epidermis 

 by some insect, the character of the light reflected from these leaves 

 being changed in consequence. In this country pea Thrips sometimes 

 affects the pods in a somewhat similar manner. 



3. INOCULATION EXPERIMENTS. 

 (a) Experiments with plum trees. 



Large numbers of inoculation experiments, in addition to those 

 described in previous papers of this series have been performed, especially 

 with Siereum purpureum. 



During 1911-12 certain inoculations with spores of Stereum pur- 

 pureum were successfully carried out for the first time. Other spore 



