Report on experimental investigations upon the intimate nature of the contagium in certain acute infective diseases / by G.F. Dowdeswell.

  • Dowdeswell, G.F.
Date:
1884
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Licence: Public Domain Mark

Credit: Report on experimental investigations upon the intimate nature of the contagium in certain acute infective diseases / by G.F. Dowdeswell. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    remarkable manner ; in the large majority of cases, including very numerous experiments not here recorded, varying only between about twenty-three and twenty-five hours. In those exceptional cases where the duration of this period materially exceeded this time, it was probably—in some instances, it appeared to me, obviously—due to the constitutional vigour of the animal, its individual power of resisting infection ; to some degree it may be due to the greater age of the animal, though it was endeavoured to avoid this cause of disturbance as much as possible, by always using animals only of about the same age, viz., nearly full grown ; the younger the animal, as is well known, the greater being the susceptibility to infection and the more rapid its course. Another cause which in some cases in my lecord of experi- ments contributed to make this period appear to be longer than it actually was, is that, where the animal was not actually observed to die before evening, it was not seen again till the next morning, when it may have been dead several hours. Neither in the case of Pasteur’s septichsemia, or infective peritonitis— the malignant oedema of Koch—is there any increase of virulence in successive inoculations after the first. The quantities requisite for fatal infection or intoxication are here infinitely greater than in the case of Davaine’s septichsemia, and the result is far less certain, in one case 0.02 cubic centimetre being fatally toxical, in another, and that one of a subsequent generation, 0.05 being innocuous. In no case, however, in any successive generation up to the sixth of transmitted infection, was a materially smaller quantity than in the first found to be toxical. The period between inoculation and death, likewise, is here more variable than in the case of Davaine’s septichaemia, dependent, in some measure at least, upon the different constitutional vigour of the animals; but there is obviously no constant diminution of this period. This investigation, as I am fully aware, is very incomplete, leaving many essential points undetermined, and that more particularly in the case of Pasteur’s so-termed septichamiia, or infective peritonitis, which, from the circumstance of its being the only instance as yet recorded of a microparasitical infective disease which can be excited by the action of a germ-free chemical irritant—deserves the most careful further investigation, with the view of elucidating the exact relations existing between these micro-organisms and the virulence of the fluids in which they occur. In this affection, I can only claim to have shown that, as in the former case, there is here no increase of virulence in successive inoculations, and that, consequently, with reference to the particular object with which this investigation was undertaken, it lends no support whatever to the doctrine of a transformation of physiological species, either through an “adaptive increase of virulence,” or in any other way. The question of the occurrence of any such change is still, as it has been lately pronounced to be by Professor Virchow,47 a fundamental one in the subject of the relations of these organisms to disease : to its elucidation and the avoidance of some errors previously made, the vastly improved and improving appliances of the microscope, more especially its highest powers now so greatly perfected, should be brought to bear more assiduously than hitherto in the requisite preliminary discrimination of the specific morphological characters of these micro-organisms. In conclusion, I must express my sincere thanks to the British Medical Association for the assistance liberally afforded, through the Scientific Grants G’ommittee, from time to time during this investigation. 47 Aildress to the International Medical Congress, 1881, Pathological Section.