Researches into the etiology of dengue / by J.W. McLaughlin.

  • McLaughlin, J. W. (James Wharton)
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Researches into the etiology of dengue / by J.W. McLaughlin. Source: Wellcome Collection.

    13/18 (page 678)
    ent series of tubes invariably revealed a pure culture, g., without any other forms of bacteria; it would seem that the methods of sterilization employed had been successful in excluding alien germs, and that those found had a common origin from dengue blood. The life history of these organisms was watched daily, and studied by means of Holman’s life-slide. In the old cultures, those which were removed by many generations from the blood, the organisms were smaller, less deeply colored, and less frequently en¬ capsulated, than those seen in the blood, or removed from it by a few [generations. When examined in water without being stained, or in other fluid media which possess a low index of refraction, the micro¬ cocci are seen in active movement (Brown movement). In those cultures which are removed by only a few generations from the blood, the cocci are seen sur¬ rounded by capsules. These are sometimes faintly | colored pinkish, and can be distinguished from the j cocci, which possess a deeper color. Two methods of generation were observed: The I drst by fission; the organisms are seen to divide; through their centres; each coccus will thus form wo others. Frequently these newly formed or¬ ganisms remain united together so as to assume the form of a rod or chaplet; this indicates that they belong to the class named streptococci. In • other cases they unite to form swarms or zooglote. These latter become more compact, the distinctions of the cocci less, the color of the mass deeper, until they finally contract into corpuscular bodies, about the size of red blood cells; these often unite to form fil¬ aments, which frequently assume the shape of a net-: work. This I have often seen when the culture was j thinned with distilled water and allowed to dry upon : a microscopic slide. This arrangement can be seen, whether the specimens are stained or not. The swarms and chaplets of. the micrococci can be much better seen in the stained preparations. A histolog¬ ical-stand, Abbe’s illuminating apparatus and ^ H. I. objective, manufactured by J. Grunow, of New York, were used in these researches. The results obtained in the following and last series , of investigations of dengue blood are to me very ! satisfactory and conclusive, inasmuch as the means adopted to exclude alien germs were, as far as I can see, absolutely perfect. The apparatus used consisted of a series of glass bulbs united and blown upon a capillary glass tube— Liebig’s potash bulbs. To one end of this apparatus was attached a new hypodermic needle, by means of a short piece of new rubber tubing. To the other end of the glass tube (which was packed with cotton) was attached an aspirator. — The following is the method used in sterilizing and using this apparatus, viz.: The series of bulbs were first chemically cleaned, one end of the tube was then packed with absorbent cotton, and the bulb heated in a furnace for an hour at 400° F. The rub¬ ber tubing, with the hypodermic needle attached, was treated with a 20 per cent, solution of carbolic acid, washed in clear water, and exposed to the tempera¬ ture of escaping steam for an hour, in the sterilizing cylinder. It was then dried in the furnace, the free ! end of the tubing slipped over the free end of the ! glass tube, and the end to which the hypodermic j needle was attached was encased with a sterilized test-tube, this was held in its place and the needle protected from air germs by means of absorbent cot¬ ton, that was packed firmly in the mouth of the test tube, and around the needle. The entire apparatus as thus arranged, tubing and needle attached, and covered with test-tube, was again put into the furnace and heated to 300° F. It was then removed from the furnace and carried to the home of the gentleman who kindly donated a sufficient amount of his blood for this investigation. He had a typical case of dengue. Flis arm was washed with soap and w'arm w^ater, dried with a freshly ironed tow^el, and then a solution of carbolic acid, sufficiently strong to quickly whiten the skin, wTas applied to that part of the arm where the puncture was to be made. A ligature wras then applied to the arm above the elbow. The test tube w^as removed from the hypodermic needle, and this wras quickly passed into the large vein, at the bend of the arm. An aspirator wras then attached to the free end of the glass tube—wffiich wras packed writh sterilized cotton—and the bulbs partially filled with blood by means of aspiration. The glass tube, next to the rubber, wras then closed and separated by the blowr-pipe, before the needle was withdrawal from the arm. These bulbs containing the dengue blood, wffiich wrere effectually closed against the admission of all germs, and wffiich contained no germs except those which entered wfith the blood from the veins of the donor, w^ere then put into an incubator at ioo° F. temperature, in order that a pure culture of the dengue micrococci might be grown in the bulbs, wfith their contained blood as the nutritive medium. The first bulb was removed with the blow-pipe, and examined at the expiration of six w eeks. The blood was examined, first, directly, wathout admixture; sec¬ ond, after treatment wfith glacial acetic acid, undiluted and in w^eak solutions; third, wath 10 per cent, solution of caustic potash and in w7eak solutions of this alkali; and fourth, finally subjected to the various aniline dyes, before referred to. In the direct examinations, a small drop of blood wras placed upon the cover-glass, this w^as then in¬ verted upon a slide, so as to obtain for examination a thin layer of blood; or the blood wras examined in y'z per cent, salt solution or a solution of osmic acid 1 to 300. In those specimens examined directly, the field appeared to be covered with blood cells and dark pigment granules; these latter wTere seen in im¬ mense numbers. When ihe blood was examined in the salt solution, or in the solution of osmic acid—this latter fixed the cells, and by giving them a faint brown color, Ten¬ dered them more distinct—it wras seen that what appeared as dark pigment granules in the direct ex¬ amination, wras now recognized as dengue micro-or¬ ganisms, with all their distinctive features. The red cells in many cases wrere absolutely crowried wfith these, wffiilst in the plasma they wrere seen free, in swarms, zooglcea, masses, and in corpuscular bodies, which sometimes united to form filaments, as in the