SCIENTIFIC COMMITTEE, SEPTEMBER 3. 



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Scientific Committee, September 3, 1907. 



Mr. E. A. Bowles, M.A., F.L.S., in the Chair, and ten members 



present. 



Mildew on Maple. — Mr. H. T. Giissow showed leaves of a species 

 of Acer attacked by the conidial form of tbe fungus Uncinula Aceris, 

 so frequent on Acer campestre. 



Currant Leaves diseased. — Mr. Saunders, F.L.S., showed leaves of 

 Currant attacked by the fungus Gloeosporium Ribis, which Mr. Giissow 

 stated had recently been found to be a stage in the life-history of the 

 fungus Pscudopeziza Ribis. 



Propagation of Potato Diseases. — Mr. Cuthbertson showed the 

 produce of two tubers of Potato which had been sent to the Committee 

 last year attacked by the fungus causing "winter-rot." Both tubers 

 had grown normally, and had prcduced a fair crop. He proposed to 

 keep these tubers through the winter in order to discover whether or 

 not the disease would appear in them. Mr. Sutton observed that in 

 certain experiments carried out by him at Reading this year it was 

 found that tubers of Potato attacked by the fungus Phytophthora 

 infestans, and employed as sets, yielded about 70 per cent, of normal 

 plants free from disease. 



Mendelian Laics of Inheritance. — Mr. Worsley brought up this 

 question with reference to the colours of certain Bean flowers which he 

 exhibited, and the need for further extended careful experiment was 

 insisted upon. 



Fig Leaves diseased. — Mr. Bowles showed Fig leaves much dis- 

 figured by irregular brown and yellow -brown patches of variable size. 

 The appearance is due to the attacks of a fungus, Cercospora Bolleana, 

 which develops its fructification on the dead leaves, and hibernates 

 in the stem of the plant, so that it is carried over from one year to 

 the next. 



Malformation of Myosotis. — Mr. Bowles also exhibited a specimen 

 of Myosotis palustris, which he had collected in Suffolk, near Ipswich, 

 having the calyx lobes much enlarged and the spike somewhat 

 lengthened. Each inflorescence on the plant had exhibited the same 

 structure. 



Mint-rust. — Plants of Peppermint from near Dorking were sent 

 badly attacked by the Mint-rust, or "snuff," as the trouble is locally 

 called. The small reddish spots which occur on the leaves in abundance 

 at this season of the year are the uredo form of the fungus Puccinia 

 Menthae, and the mycelium of the fungus hibernates in the underground 

 portions of the plant, so that no cure can be suggested. If external 

 conditions are favourable, the disease is sure to make itself evident in 

 the succeeding year. 



Galls on Walnut Leaf— My. W. C. Worsdell, F.L.S., sent from 

 Westmorland leaves of Juglans regia having rather large swellings on 

 the upper surface of the leaf, with corresponding hollows on the lower 

 surface. These malformations, which are frequent on Walnut leaves, are 

 due to the attack on the leaf of a mite, Eriophyes tristratus var. erinea. 



