SCIENTIFIC COMMITTEE, APEIL 6. 



XXXIX 



Scientific Committee, April 6, 1909. 



Mr. E. A. Bowles, M.A., F.L.S., in the Chair, with seventeen members 

 present and Messrs. E. Laxton and J. H. Drummond, F.L.S., visitors. 



Gummosis in Lemon. — Mr. Giissow reported that the specimens of 

 Lemon shown by Mr. Worsley at the last meeting had been examined 

 microscopically. "After dissolving the gum in warm water, at each of 

 the places where it exuded a wound was to be seen extending some 

 way into the wood. The injured portions had no connection with 

 each other, but were well denned nearly all round the stem. The dis- 

 tance between the two places where gum was seen oozing out was about 

 4 inches. The bark was peeled off and some of the gum was transferred 

 with a sterilized needle to a cover glass, and was diluted with distilled 

 water. After drying this preparation it was stained for bacteria, 

 and in every case a large number of bacteria were revealed. The 

 presence of the bacteria does not certainly prove that the gumming 

 was caused by them, but the examination plainly showed that the injury 

 could not have been due to some cause or other within the range of the 

 root. Mr. Worsley kindly sent me the root and stem of the diseased 

 Lemon, and the roots were found to be perfectly healthy, with a good 

 many fibres and small rootlets ; the stem just above the root showed 

 near a thorn an injury which, according to additional information 

 from Mr. Worsley, had first exhibited the gumming. The specimen 

 examined was a seedling. It is frequently the case that bacteria gain 

 entrance in the place of grafting, and cause profuse outflow of gum in 

 all kinds of stone fruits. A pure culture of the organisms has been made> 

 and it will be used in infecting a young Cherry tree. The bacteria 

 isolated from Cherries, Plums, arid Peaches which showed gumming 

 bore great resemblance to those isolated from the Lemon. The withering 

 and flagging, and the silvery appearance of the shoots and leaves above 

 the place of injury are certainly the natural results of the sap-conducting 

 vessels being clogged by the gum." 



Inheritance of character in Pea seeds. — Mr. A. W. Sutton, V.M.H., 

 exhibited a long series of preparations showing the seeds of plants raised 

 by crossing a Pea which he found growing wild in Palestine (? Pisum 

 arvense) with forms of the cultivated garden Pea (Pisum sativum), and, 

 with bicolor-flowered Peas (Pisum arvense), &c. Twenty-two crosses 

 were made in 1907, and four of these failed to produce mature seed in 

 Fj ; four died off before flowering in F } ; seven flowered but produced 

 no seeds ; seven only produced any seeds in F 2 (the latter were shown on 

 cards 1 to 7). In most cases it would appear that the plants were almost 

 or quite sterile. On cards 8, 9, and 10 were the results of crosses made 

 between the Palestine Pea and Pisum sativum by Mr. Darbishire, and 

 grown at Eeading. They practically confirm Mr. Sutton's experiments. 

 Mr. Sutton also exhibited a growing plant of the wild Pea from Palestine, 

 and a plant of Pisum quadratum (?) grown from seeds received from 

 Kew. This plant much resembles the Palestine Pea in all respects except 

 the foliage. He also exhibited a collection of the various forms of seeds 

 of the garden Pea (Pisum sativum), and of bicolor blooming types 



