Abstract
LONDON Royal Society, May 21. SIR PATRICK LAIDLAW and W. J. ELFORD: A new group of filterable organisms. A group of filterable saprophytic ui-geuiicuiis has been discovered in sewage. In the normal course of their development, they have small forms of about the size of vaccinia virus (0 125-0-175 [Jt), though larger forms also occur (0-5 [L or more). Cultures are readily obtained by filtering mixtures of sewage and Fildes's broth through membrane filters of appropriate porosity, and incubating the filtrates at 30 ° C. They can be maintained in subculture in indefinite series. Three strains have been isolated which differ in their cultural characters and also serologically, though morphologically they appear the same, and they all show the same end-point in filterability. These organisms are of interest in view of the small forms, which although comparable in size with some of the viruses, can nevertheless lead an independent existence. It is, as yet, uncertain how the organisms should be classified. MARION A. WATSON (HAMILTON): Factors affecting the amount of infection obtained by aphis transmission of the virus Hy. III. Experiments have been carried out in order to show the effect of various factors on the percentage of infection obtained with the virus Hy. Ill in tobacco, using its insect vector Myzus persicce. A maximum percentage infection was obtained during the winter months and a minimum during the summer months. The percentage infection increases with the number of aphids used per plant, and the relation between the numbers of infection obtained for each aphid number shows that the infections are local and independent. The percentage infection increases with increased feeding time on the healthy plant, but there is no indication of a preliminary time period in which no infection is obtained. The percentage infection decreases very rapidly with increasing time on the infected plant from 2 minutes to 1 hour. After 1 hour it increases slightly with further increase of the feeding periods. R. RTJGGLES GATES: Genetical and taxonomic investigations in the genus Oenothera. This paper presents the results of a three years' genetical survey of the genus Oenothera in eastern Canada and adjacent areas. By combining genetical with taxonomic methods, a fuller knowledge is attained of the wild populations in a particular area than has been possible in any case hitherto. Thirty-two new species and varieties are described, as well as many smaller variations, and much light is thrown on the geographical distribution of these and other forms, as well as their relationships. There are indications of movements from south to north in several different lines of descent, and also of a coastal series of forms with strongly bent stems. Six of these new species have produced trisomic mutations, most of them directly from wild seeds, and one a triploid mutation, which shows that the mutation phenomena are not the result of cultivation. The catenation in all the species examined is a ring of 14 chromosomes. Certain prairie species show marked alteration of habit when grown in England, and a new category of evanescent characters is made for differential characters which appear only at certain stages of development.
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Societies and Academies. Nature 137, 918–919 (1936). https://doi.org/10.1038/137918b0
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DOI: https://doi.org/10.1038/137918b0