cxliv PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



infection takes place below ground. In some instances there were old 

 wounds through which the infection might have taken place, in others 

 no abraded surface was noticeable. Whether other species of Stcreum 

 are capable of setting up the disease, and other matters, are to be inves- 

 tigated later on, when more material is available. Meanwhile this com- 

 munication should be read in full, and its substance disseminated through 

 all horticultural circles." 



Potato Tumour. — Dr. Cooke also added the following investigation : 

 " The young Potatos which were sent to the last Committee were 

 remarkable in appearance, the whole surface being corrugated and dis- 

 torted by some parasite which it was necessary to discover. At the same 

 time the distorted tubers were much darker in colour, and softened. Cut 

 in section, the centre retained the colour and texture of healthy Potato, 

 but at the periphery, immediately beneath the cuticle, it was excavated with 

 brown cells. These cells contained subglobose brown bodies (about 

 25 x 20 ju) on hyaline pedicels, resembling much the gonidia of Pythium. 

 This parasite being quite new to me, and unnoticed in any work to 

 which I had reference, I consulted Mr. Massee, who had made special 

 study of this group, and he at once informed me that the same disease 

 appeared last year near Birkenhead, where it completely destroyed a field 

 of Potatos, and that it evidently was allied to Pyt hium, and had been 

 found in Germany, and called Ghrysophlyctis cndobiotica (Schilbersky, 

 Ber. Sent. Bot. Gesell. p. 36, 1896). As far as we have been able to 

 discover, this genus has never been described, but seems to be a close 

 ally of Pythium, and very similar to the fungus which causes Beetroot 

 tumour, and known as CEdomyccs leproides or Urophlyctis Icproidcs. 

 Although I did not find them, Mr. Massee informs me that the first- 

 formed spores are subglobose, produced at the apex of a hypha, which 

 has a large vesicular swelling just below the spore, exactly as in the 

 Beet-root disease. It is very unsatisfactory that, as in the case of the 

 Larch disease just under notice, these destructive fungi should be simply 

 named in more or less obscure foreign journals, and not properly 

 described, so that they may be recognised and investigated. In the 

 present instance I believe that I am justified in stating that Mr. Massee 

 has a memoir in preparation, detailing his own investigations together 

 with all that is hitherto known of this new ' Potato tumour.' I am 

 afraid that the disease is of such a nature that it may be classed as 

 incurable, and can only be stamped out by vigorous measures of de- 

 struction." 



A unanimous vote of thanks was given to Dr. Cooke, V.M.H., for his 

 three reports. 



Influence of Scion on Stock. — Mr. W. B. Latham, of the Botanical 

 Gardens, Edgbaston, Birmingham, sent a bough of a Laburnum, from 

 which a cluster of shoots of Cytisus purpureas had grown out. It 

 appears that the tree was purchased some twenty-seven or twenty-eight 

 years ago as a young plant of C. purpureus grafted on C. Laburnum. 

 The scion grew very well for a year or two on the stock, till a strong shoot 

 grew out below where the graft was inserted. This was cut off to save 

 the graft, but the graft quite died out soon afterwards. The stock was 

 left to grow into a Laburnum tree, which is now from fifteen to twenty 



