A survey reported by Sawyer and Whitman (1) showed that there is a broad zone through the center of Africa in which there is a high incidence of humoral immunity to yellow fever. This zone extends from the West coast across central Africa and into, but not through, Uganda. Following this disclosure an epidemi ological investigation was undertaken, one phase of which was an attempt to isolate yellow fever virus from localities in the edge of the presumably endemic zone.In attempting to isolate virus numerous persons were seen who were suffering either from an illness suggesting yellow fever, or from pyrexia of unknown cause. From many such persons blood was drawn, and as soon as possible thereafter the serum was in oculated intracerebrally2 into mice. Subinoculations were done from mice which became ill. In this manner several transmissible infective agents were isolated.The purpose of this paper is to report the isolation of one such agent, which we call the West Nile virus, and to describe some of its properties. Although this virus was isolated from the blood of a human being, the circumstances of its isolation were such that nothing is known regarding the illness produced by the virus in the human subject.An African woman, aged 37 year8, was seen by one of us (A. W. B.) in Uganda. This woman reported to the officersof the sleeping sickness survey and was not subjected to other examination than that which is usual in the routine of this survey, except that her temperature was taken. Her oral temperature was 100.6°F.She denied feeling ill, perhaps to avoid hospitalization. Nevertheless a sample of her blood was taken, and serum from it was inoculated intracerebrally into mice.The woman was not seen again until 3 months later, when another speci men of her blood was taken. At this time she denied that she had been ill at or near the time she was seen in December. She was not alto gether co-operative and it is possible that she withheld pertinent facts.Of the ten mice inoculated with the original blood serum of this woman, only one survived. The others became ill 6 to 8 days after inoculation and either died or were sacrificedfor subinoculations. The infectious agent was readily established in mice and was preserved for months in the frozen state. Subinoculations in series have been done by injecting each mouse intracerebrally with 0.03 cc. of the supernatant from a suspension of infected mouse brain in saline. The virus is now (September 15, 1939) in its 53rd passage, and there have been no sur vivors since the first mouse passage. FILTERABILITY OF THE AGENTIt was found early in these studies that the agent readily trav erses Berkefeld filters of V, N, and W grades and Seitz EK asbes tos pads. Mice invariably succumbed following intracerebral inoculation of filtrates of the supernatant from 10 per cent sus pensions of infected mouse brain. The following experiment shows that filtrates from Berkefeld V and N candles contain virus in high titre.Brains of ill mice of the 14th passage were ground in a mortar wi...

Over the past two decades or so, historians of science have lamented the limitations of internalist history and celebrated the rise of contextual history. Historians of technology, however, have not accepted the location, by historians of science, of technology within the context of science. Historians of technology see an interaction, rather than contextual dependency. A few historians and sociologists of science and technology are now suggesting `networks' and `systems' as the preferred version of the interactive approach, with the interaction occurring not simply between science and technology, but also among a host of actors and institutions. Networks and systems eliminate many categories in favour of a `seamless web', which may lead to a new appreciation of the complex narrative style.

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ODONT. ‡ THE POSITIONAL CHANGES that may occur in the gingiva following scaling, root planing, and oral hy giene (such as recession, reattachment, and variations in gingival width, pocket depth, and location of the mucogingival junction) have not been studied system atically. However, it is generally assumed that some gingival recession and/or some change in crevice or pocket depth may occur after scaling and root planing and that there is no change in the position of the mucogingival junction. The location of the free gingival margin, the crevice depth, and the position of the mucogingival junction can be determined accurately with the cementoenamel junction as a fixed reference point. 1-5 Thus, it is possible to evaluate clinically any biometric changes in the relationships between these structures before and after scaling, root planing and oral hygiene. Recent reports indicate a tendency for the width of the attached gingiva to increase with age. 6,7 Teeth in labial version and teeth with adjacent muscle attach ment and/or frenum involvement of the attached gin giva, generally have a narrow zone of attached gingiva. 8 With orthodontic hypereruption of teeth, the width of the attached gingiva may be increased with no change in the position of the mucogingival junction. 9,10 Var ious mucogingival surgical procedures, 11-21 may also increase the width of the attached gingiva, changing the position of the mucogingival junction. The effects of other periodontal procedures on the width of at tached gingiva and mucogingival junction are not known. The purpose of the present study was to assess certain clinical changes that will occur in the gingiva after scaling, root planing, and oral hygiene in areas of advanced or severe gingival inflammation. The param eters studied were location of the mucogingival junc tion, crevice depth, attachment level, height of the gingival margin, and width of the keratinized gingiva. MATERIALS AND METHODS * This study was submitted to the Horace H. Rackham School of Graduate Studies, The University of Michigan, by the senior author in partial fulfillment of the requirements for the degree of Master of Science in Periodontics.