F. T. Brooks and M. A. Bailey 195 



seemed to show a gradual improvement, i.e. their foliage appeared to 

 become more normal in appearance. During February, 1913, these 

 seedlings, then about a foot high, were cut down in order to be used 

 for scions. In May, 1913, about fifty of these 400 Victoria seedlings 

 were still silvered and by 1914 only about ten remained silvered, so it 

 is clear that these plants gradually grew out of the affection. 



While visiting the Agricultural Research Station at Long Ashton, 

 Bristol, during July, 1913, Professor Barker called the attention of one 

 of us to the presence of silver-leaf in seedlings of certain kinds of Ribes, 

 Rubus, and Primus. These seedlings had been planted out in May of 

 the same year in soil which had been broken up from grass land two 

 years previously and had not been manured. The following is a summary 

 of the observations made at the time of the visit: 



Red Currant {Raby Castle). 



Silvering common but more marked in old than in young leaves. 



Red Currant {Sweet Red). 



Plants appear to be growing out of silvering. 



Red Currant (Ogdens). 

 No sign of silver-leaf. 



White Currants (White Dutch Cut Leaf). 

 Plants appear to be growing out of silvering. 



Rubus innominatus Kuntzeanus. 

 Numerous plants with silvered foliage. 



Loganberry. 

 Silvering present but not conspicuous. 



Prunus sfinosis-nmwi. 



One of the five plants was markedly silvered. 



It was not possible to examine these silvered plants microscopically, 

 but to the naked eye they appeared to be typically silvered, although 

 most of them were growing out of the affection. 



After treatment in the usual manner^ other batches of plum seeds 

 of different varieties (Victoria, Monarch, Greengage) gathered in 1913 



1 Tliesc seeds were treated in the following manner: the plum stones were placed in 

 damp soil as gathered and when the collection was complete the stones were washed and 

 then immersed in shallow boxes of sand previously dry heated to 100° C. The bo.xes 

 were then placed in a cold frame and kept damp. Early in January the seeds were taken 

 from the stones and then planted in soil which had been treated with toluol and placed 

 in a greenhouse from which frost was excluded. Under these conditions germination 

 proceeded. 



