SCIENTIFIC COMMITTEE, OCTOBER 27. 



clxxix 



out, and especially by taking care not to plant Potatos again on ground 

 where warted Potatos have been found, until the soil has been thoroughly 

 disinfected, and then to cultivate some other crop for two or three years. 

 If the Colorado Bhizoctonia finds its way to us across the Atlantic, our 

 Potato crops will be in grave danger from two such powerful enemies." 



Dr. Magnus, however, sent a note to the "Gardeners' Chronicle" 

 saying : " Dr. Cooke is mistaken in thinking that I have identified the 

 fungus in the warts of the Potatos as UropJilyctis leproides (Trab.), P. 

 Magnus, which causes the Beetroot tumours. I have never seen the warty 

 Potatos, which I regret very much, and of course I have written nothing 

 about them. But the description given by E. Schilberszky in Bcrichte cler 

 Deutschen Botanischen Gesellschaft, vol. xiv. (1896), pp. 36, 37 ; and the 

 description and figures given by Mr. M. C. Potter in the Journal of the 

 Board of Agriculture, vol. ix., December 1902, p. 320, plate iv., seem to 

 me to show that the fungus of the warty Potato-disease is entirely different 

 from Urophlyctis leproides (Trab.) in the Beetroot tumours, and belongs 

 apparently to another genus, called by Schilberszky Clirysoplilyctis, with 

 the species C. endobiotica. I should be very glad to receive material of 

 the warty Potato-disease, in order that I may study it." 



Wound Parasite of Apple-trees. — Dr. Cooke, V.M.H., reported : " Mr. 

 Fred. Chittenden, of Chelmsford Technical Laboratory, sent specimens of 

 Hydnum Schiedermayeri, which is a wound parasite of the Apple-tree, and 

 was found growing on an old- Apple tree at Maldon in Essex, for the first 

 time recorded in Britain, although it is noted in Massee's 1 Plant Diseases,' 

 and figured. It formed a strip of about four feet growing through the 

 bark. It has a nodulose appearance, of an ochry yellow or flesh colour, 

 and the nodules develop long spines which are covered by the hymenium 

 producing the spores. According to Thiimen this fungus is very 

 frequently destructive to Apple-trees, the spores entering through a 

 wound or fissure in the bark." 



Tomentum on Vine-leaves. — Dr. Bonavia sent leaves to show how 

 closely natural woolliness, or tomentum, resembled the red-spider's web, 

 and that it was impossible to distinguish between them by the naked eye. 

 Mr. Saunders observes : "I should not think it could be possible for any- 

 one to distinguish between the tomentum on the leaves and the web spun 

 by the red spiders with the naked eye, unless the webs only covered parts 

 of the leaves, in which case the undersides of the leaves would have a 

 patchy appearance ; but the similarity between the web and the tomentum 

 is so great, that otherwise no ordinary eye could detect the difference. 

 Under the microscope the threads of the tomentum are twisted, and do 

 not lie so straight as the threads of the webs." 



Scientific Committee, October 27, 1903. 

 Dr. M. T. Masters, F.R.S., in the Chair, and ten members present. 



Crassula Aitoni. — Mr. Odell showed specimens of this Karroo plant of 

 South Africa, remarkable for bearing, in lieu of flowers, leaf-buds, each 

 consisting of two pairs of minute leaves. 



Begonia bi- sexual.— -Mr. Worsdell showed malformed flowers with 



