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.

    15/18 (page 679)
    jelly culture. Cover-glass preparations of the blood, from this culture bulb, were subjected to the various aniline stains. The indisposition to hold any of these dyes, except the methyl-blue potash, was as distinctly manifested as in the fresh dengue blood. The only difference in the appearance of the micrococci as observed in the fresh blood and that obtained from the culture bulbs is this: The organisms, when stained, appear larger in the latter than they did in the former; this, I think, is due to the fact that in the culture bulbs they are more frequently encapsulated. When both cocci and capsule are stained, the size is apparently larger. The remaining bulbs were examined six weeks later. They all contained pure cultures of the dengue streptococcus, with disintegrated blood cells. These organisms were seen in zoogloea, swarms, and in compact corpuscular masses; these were often united to form filaments. Normally shaped blood cells were found in only one of these last series of bulbs. I think their preservation in this bulb was due to a layer of coagulated serum which had formed over the surface of its contained blood. Many of the blood corpuscles in this bulb were more or less disinte¬ grated, those which retained their shape were clouded by coagulation of the cell protoplasm, which con¬ cealed the organisms they contained to a greater or less extent. These, however, could be seen in £reat numbers, when the blood was examined in a weak alkaline or acid solution, which rendered the cells more transparent. None of the bulbs, when opened, had the least odor of putrefaction, and the only micro¬ organisms which they contained were those peculiar to dengue. Pure cultures of these were found in each of the series of bulbs, and were seen in their various stages of development, e. g., with and without capsules, in swarms, in zoogloea masses and in corpuscular shaped bodies, frequently united to form variously shaped filaments. In these filaments the corpuscular masses, ; and often the cocci which formed them, could be seen ! faintlv outlined. j This ends, at least for the present, these investiga¬ tions. No one better knows than myself the incom- j pleteness of this work, nor appreciates better the possibilities which might have resulted from its con¬ tinued prosecution. The want of time and facilities for its proper execution prevented me from under¬ taking any additional labors in this matter. The j investigations were undertaken without bias, and the conclusions arrived at are the result of careful, con- i scientious work. Whether these conclusions are true or false must be decided by the future. ' I am greatly indebted to Dr. R. Munger, of San Antonio, Texas, for excellent micro-photographs of j dengue blood, obtained from the first culture bulb. , The zeal and patience displayed by him in this work are characteristic of the lover of science, while the excellent results obtained mark him as an expert in these matters. Many efforts were made by him to photograph the specimens colored with methyl-blue; j success was attained only with those specimens which were stained after Sternberg’s method for photograph- j ing micro-organisms, viz. : A drop of sulphuric acid was placed upon the blood dried upon the cover-glass; this was allowed to re¬ main for a minute, and' then washed off with distilled | water. The cover-glass was then floated, blood side downward, upon the following solution, in a watch crystal, viz.: Iodine.grms. 3. Iodide of potassium. “ 5. Distilled water. “500. After a few minutes’ exposure the preparation will be found to present a deep orange color, which gives the desired contrast in a photographic negative. The | micro-photographs which he obtained from specimens ; stained by this method displayed the blood cells, in i which appeared many micrococci, while zoogloea and swarms are seen in the blood plasma. In conclusion, I desire to express the regrets I | feel in not being able to complete these investiga- | tions. Zopf, Koch and others indicate among the questions to be answered in a thorough study of any bacteria, the following: 1. Shape, size, color and details of structure, e. g., flagella, peculiar envelope, etc. Character and speed of movements. 2. Character of natural habitat. Artificial media best adapted to growth and reproduction. Stages of development passed through. • Formation of zoog¬ loea spores, filaments, rods, cocci, “swarms.” Con¬ ditions under which such formation occurs. Charac¬ ter of colonies formed in firm culture media. 3. Capability of producing fermentation, putrefac¬ tion. Character of decomposition products, volatile and other, formed in various nourishing media. 4. Behavior toward oxygen at normal and altered pressures. Behavior toward other gases. 5. Effects of various temperatures on movements, germination, etc. 6. Behavior in relation to light (phototonic prop¬ erties). Behavior toward electricity. 7. Behavior toward antiseptics and poisons. 8. Are the forms under investigation found in a dis¬ eased organ or tissue. What is the effect of inoculating animals of different orders and species with pure cul¬ tures. If virulent, can the virulence be attenuated by exposure to air, to antiseptics, to heat, or by re¬ peated “fractional” cultures. Under what condi¬ tions. Does the inoculation of attenuated germs have a cumulative effect if repeated at short intervals. Does one inoculation give immunity towards a second made with virulent microbes. It will be seen that the character of investigation indicated by these questions could only be carried out by persons possessed of an abundance of time and money, and a willingness to devote both to such labors, or under the auspices and at the expense of the State or Federal Government. In view of the bril¬ liant results already attained by such investigations, i. e.y the protection furnished, by inoculation with the attenuated microbes, against the following diseases, viz. : small-pox, hydrophobia, anthrax, yellow fever,(?) hog typhus and chicken cholera, it would seem a wise, humane and economical policy on the part of the Slate or Federal Government to encourage, by money ap¬ propriation, such investigations. Among the proba-.