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Macrophoma tumefaciens Shear was shown experimentally to be the causal agent of the galls in uninjured Populus balsamifera L.Penetration of the intact cuticle and epidermis was direct. After negotiating the epidermal layer, the fungus ramified both inter- and intra-cellularly. Within the inner periderm and outer cortex there developed intervening pockets of plesionecrotic tissue partially ingressed by fungus hyphae. Meristematic activity of the phellogen was accelerated, and new lenticels were stimulated in the inner periderm and cortex; such meristematic activity corresponded with the final development of the stromata and mature pycnidia; it persisted and seemed to prevent or delay considerably the ingress of the fungus. A cicatrice, consisting of rapidly dividing cortical parenchyma, was also stimulated; meristematic cells surrounding the holonecrotic area remained unchanged in appearance until hyphae came in contact with them.Development of pycnidia, and stimulation of hypertrophy of the phloem, cambium, and xylem are described.

Summary Cylinders filled with Orthic Black Ah material were leached over a 2-year period with distilled water or with aqueous extracts of aspen or black poplar leaves that were collected late in the growing season. Actual losses from the soil and chemical analyses of the leached soil indicated that the aqueous extract of aspen poplar leaves imposed greater changes on the chemical properties of the soil than did the extract of black poplar leaves. These changes were particularly noticeable for pH, total and exchangeable Ca, and 0.1N NaOH-extractable C. The aqueous extract of aspen poplar leaves acidified the soil more strongly than the extract of black poplar leaves, even though there was little difference between the two extracts in polyphenol and polysaccharide content and the total acidity of the black poplar extract was about twice that of the aspen poplar extract. Aqueous extract of weathered aspen poplar leaves was no more effective than distilled water.

THERE is a general feeling that once the folklore of a county has been published there is no more to be done. Miss Charlotte Burne's monumental book on Shropshire is a case in point. Yet since the War I have collected half a dozen pieces of folklore in the county not mentioned by her: one of them, the Aston-on-Clun Arbor Tree is of outstanding importance. I have no doubt that similar rewards await researchers in other parts of the country and indeed in parts of Shropshire not known to me. The dressing of the Arbor Tree at Aston is one of the most remarkable survivals of nature worship in Britain. The village of Aston lies a few miles west of Craven Arms up the Clun valley which here forms a big bulge into the Welsh Border. The area is very peculiar in itself belonging both to England and Wales with a wild scenery of its own special quality abounding in abrupt, wooded hills. The Arbor Tree is a large black poplar standing at a cross roads in the centre of the village of Aston-on-Clun. To its major branches are attached seven or eight long poles from the extremities of which flags are hung. These flags are renewed every year; according to local tradition to commemorate the wedding of a local heiress who was so charmed by the gesture that she left a sum of money for the custom to be performed annually on 29 May. And indeed the lord of the manor, John Marston, did marry a certain Mary Carter on 29 May, 1786. The date is significant, for this anniversary of Charles II's restoration in I66o, celebrated as Royal Oak Day, has attracted to itself many more ancient spring ceremonies, notably the Castleton Garlanding. It seems likely therefore that the wedding ceremony which would be a day of local rejoicing was fixed to coincide with this other older village celebration and then endowed as recorded above. Here at Aston then we are faced with a unique survival of tree dressing comparable with the sacred well and bush dressings of other parts of the British Isles. Unfortunately the Marston family

In the preceding paper (7) it was noted that the true mistletoe, Phoradendron, derives very little if any carbohydrate from its host, while the dwarf mistletoe, Arceuthobium, draws heavily upon the photosynthate of its host. These findings imply that Phoradendron is capable of furnishing its own energy requirements but say little regarding the extent of dependence of Arceuthobium upon its host for carbohydrates. The aerial shoots of Arceuthobium frequently exhibit an off-green color which Peirce (9) claimed is due to an abundant supply of chlorophyll that is often masked by dark pigments in the epidermal cells. Heinricher (6) described green-colored bodies in the cells of the endophytic system, however, this observation was not confirmed by Peirce (9) or Kuijt (8). A capacity of Arceuthobium to provide much of its energy requirements was implied by findings of Weir (16). He conducted a test on 8to 12-year old lodgepole pines in which 6 infected and 6 uninfected trees were repeatedly defoliated. During the second year the 6 infected trees continued to live while the uninfected trees had died. He suggested that under such conditions the mistletoe may contribute to the nutrition of its host but he added that mutual subsistence on sto.red materials in the infected region of host stems may explain the results. On the other hand, Buckland and Marples (2) noted that defoliation of western hemlock by the hemlock looper had a much more detrimental effect on dwarf mistletoe infected trees than on healthy trees. When Rediske and Shea (11) exposed aerial shoots of Arceuthobium americanum Nutt. infecting Pinus murrayana Grev. and Balf. seedlings to C1402, they noted a marked fixation of C14 in the shoots and movement of label into the host plant. This evidence was used to support their claim that the decline of the host plant normally associated with Arceuthobium infection is not a direct result of parasitism by the mistletoe. Freeland (5) analyzed leaves of Phoradendron flavescens (Pursh.) Nutt. for chlorophyll and found that both chlorophyll a and chlorophyll b were present. Apparent photosynthesis was measured and a net rate of CO2 fixation was determined. The mass of photosynthetic tissue produced by some species of Phoradendron has prompted the speculation that a symbiotic relationship might exist between the true mistletoe and its host. Wagener (15) noted that junipers heavily infected with Phoradendron juniperinum Engelm. will often have the entire upper portion of their crown replaced by mistletoe foliage. After an extremely cold winter, which killed the mistletoe, severe crown die-back was observed. He concluded that when the functioning mistletoe foliage was killed the very small amount of host foliage remaining was unable to support the crown and it died. Phoradendron infections are frequently found to terminate branches of its host (3, 15), that portion of the host branch distal to the site of infection is suppressed and killed with the proximal portion subsequently "sustained" by the mistletoe. Similar conclusions were drawn from defoliation and girdling experiments involving the European mistletoe Viscum albumt (14). Infections of Viscum were observed to prolong the life of denuded branches and even whole trees but such a situation could never be maintained for an extended period of time. The concept of symbiosis was not supported by findings of Seledzhanu and Galan-Fabian (12) who fed C1402 to foliage of Viscum infecting black poplar. They observed fixation of C02 by mistletoe leaves during all seasons of the year. Movement of C14 into adjacent mistletoe shoots was noted within 2 hours as well as into the endophytic system and to a small extent into the host tissue. The authors concluded that the transfer of organic materials between mistletoe and its host occurs only to a very limited extent. The purpose of the investigations reported here was to determine to what extent mistletoes can contribute to their own carbon nutrition and possibly to that of their hosts. This has been attempted primarily through C1402 feeding experiments, in which the photosynthetic products of mistletoe shoots were traced by radioautography and analyzed chemically to determine their similarity to carbon fixation products in other tissues. 1 Received for publication March 30, 1964. 2 This work was supported in part by National Science Foundation Grant G-13070. 3 Present address: Department of Botany and Plant Pathology, Purdue University, Lafayette, Indiana.

Arnold and Russell (1960) described Cucurbitaria staphula and its conidial state Pseudodichomera. They reported a second conidial state described as having allantoid to ovoid conidia (2.0 X 0.5 ,u) found in the same stroma as the loculus containing the Pseudodichomera state. They were unable to establish the connection of this microconidial state with the Cucurbitaria staphula in single-spore culture on 2% potato dextrose agar. At Saskatoon single-ascospore isolations were made from natural material on galls of black poplar collected at Beaver Creek and maintained on Czapek's agar containing yeast extract. They were subcultured on Czapek's agar containing xylose 20 g/I., dulcitol 1.0 g/1., raffinose 10 g/1., arabinose 5 g/1., galacturonic acid 0.5 g/I., and glucuronic acid 5 g/I. as additional sources of carbon. The fungus grew slowly and colony size was limited ; best growth was obtained at 18 and 25 °C. Pycnidia of two types were produced depending on the medium used, one containing the macrospores of the Pseudodichomera state and the other a

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The black poplar (Populus nigra L.), especially the variety known as the Lombardy poplar, is one of our most beautiful ornamental trees. It is, however, subject to diseases which shorten its life. In the United States these diseases apparently have not been studied to any extent, as there is a lack of literature on the subject. During the spring of I916, many reports were received by the United States Department of Agriculture concerning a serious blight of newly transplanted black poplars. In one instance, every tree in a lot of thirty was killed back by cankers. In a second instance, nearly all of 630 trees were badly infected with cankers, and at least one fourth of them were killed back to the point of the infection. An examination of cankers from the trees mentioned above