Part 25

Algæ, genera: Sarcina, Leptothrix.

Schizomycetæ, or Bacteria, genera: Micrococcus, Rod-bacterium, Bacillus, Spirillum.

Micrococci (Sphærobacteria of Cohn) are asserted (under certain conditions) by Letzerich, Wood, and Formad to be causative of diphtheria; Ogston has found them in ordinary pus; Rindfleisch, Recklinghausen, Waldeyer, Birch-Hirschfeld, and others report them to be always present in the abscesses of pyæmia; Buhl, Waldeyer, and Wagner state their occurrence in intestinal mycosis; Eberth, Köster, Maier, Burkhardt, and Osler, in ulcerative endocarditis; Orth, Lukomsky, Fehleisen, and Loeffler, in erysipelas; Coats and Stephen in pyelo-nephritis; Friedländer, in pneumonia; Eklund (Plax scindens) in scarlet fever; Keating and {142} Le Bel, in measles; Leyden and Gaudier, in cerebro-spinal meningitis; Carmona del Valle, in yellow fever; Prior, in dysentery; Gaffky, Leistikow, Bokai, and Bockhardt, in gonorrhoea; besides other similar observations by numerous writers.

Bacterium termo is regarded by leading authorities as the special ferment or causative agent of putrefaction (Billroth, Cohn).

Bacillus includes, hypothetically at least, several species; as Bacillus subtilis, the innocent hay-fungus; Bacillus anthracis, the microbe of malignant pustule (anthrax, milzbrand, charbon) and the splenic fever of sheep; Bacillus typhosus (Klebs, Eberth, Meyer) of typhoid fever; Bacillus lepræ (Hansen, Neisser, Cornil, Koebner) of leprosy; Bacillus malariæ, reported as having been demonstrated by Klebs and Tommasi Crudeli, Marchand, Ceri, and Ziehl; Bacillus tuberculosis (Koch, Baumgarten, 1882); the bacillus of malignant oedema (Gaffky, Brieger, Ehrlich); that of syphilis (Aufrecht, Birch-Hirschfeld, Morrison); of glanders (Loeffler, Schuetz, Israel, Bouchard); of pertussis (Burger); besides the Actinomycosis of Israel, Ponfick, Bollinger, and others. Koch has very recently (1883) been reported to have discovered in Egypt the bacillus of cholera.

The oval and spherical organisms described by Richard and Laveran as found in the blood of malarial patients resembled micrococci rather than bacilli.]

Spirillum (Spirochæta of Ehrenberg) has its best ascertained example in the minute forms first observed by Obermeier, and afterward by many other observers, in the blood of patients suffering with relapsing fever. They have been found present in the blood only during the febrile paroxysm, disappearing in the intermission and through convalescence.

Hastening to close our consideration of this subject, we may note, without much argument, a few of the points of difficulty needing yet to be more fully illuminated by {143} careful observation before any form of the germ theory can take its place as an established doctrine in etiology:

1. The absence of the characters belonging to definite organisms in the easily-studied virus of small-pox and vaccinia stands, a priori, against the probability of such organisms being essential to the causation of other enthetic diseases.

2. Analogy in nature, showing the commonly beneficial action of nutritive processes in re-appropriating the products of organic decay on a large or on a small scale, makes the scavenger theory of the general function of minute cryptogamic organisms more probable, per se, than that which holds many of them to be destructive parasites or poison-producers in the bodies which they may inhabit. Few well known parasites are capable of causing death in higher animals or in man.

3. These microbes are among the minutest objects which can be studied under the microscope. Bacteria average about 1/9000 of an inch in their longest diameter; micrococci and spores (Dauersporen, Billroth) are yet smaller. Much care, therefore, as well as skill, must be exercised in making observations upon them. Huxley asserted a few {144} years ago that a distinguished English pathologist had mistaken for movements of minute living organisms the "Brownian movements" seen in the particles of many not living substances under a high magnifying power. One observer, at least, considers that the forms designated as bacteria and micrococci, etc. are either forms of coagulated fibrin or granules from morbidly-altered blood-corpuscles (zoogloea of Billroth, Wood, Formad, and others). Koch denies the validity of the observation of organisms in tubercle by Klebs and Schüller, while insisting upon his own demonstration of a bacillus tuberculosis. Authorities must, by mutual confirmation or correction, remove these obscurities.

A chemical test much relied upon is, that bacteria resist the action of acids and alkalies, which destroy granular material of animal origin; also, that all these organisms are deeply stained by aniline dyes and by hæmatoxylin. The most decisive test, however, is cultivation in a liquid sterilized by heat. Koch prefers a process of dry culture for the bacillus of tubercle.

Gradle (Lectures on the Germ Theory of Disease, Chicago, 1883, p. 28) says that the absolute criterion of the life of bacteria is their power of multiplication.]

4. Bacteria and micrococci have been abundantly discovered (Kolaczck; J. G. Richardson) in healthy bodies upon the various mucous membranes and in the blood. The correctness of such observations has been denied, but, so far at least as the mucous membranes are concerned, it has been well established by Nothnagel, Sternberg, and others. Bacteria have sometimes been found in countless numbers in fecal discharges.

5. Bacteria become most numerous in materials of a septic or infectious character after their period of toxic intensity has passed by.

6. Suppuration can be produced (Uskoff, Orthmann) without the presence of minute organisms of any kind. Bacteria have been found {145} under Lister's antiseptic dressings without suppuration following. Paul Bert destroyed all the microbes in a septic liquid, and yet found it to retain its poisonous quality. Rosenberger (1881) has made similar observations.

Panum, Coze, and Seltz, Bergmann and Schmiedeberg, Hiller, Vulpian, Rosenberger, Clementi, Thin, and Dreyer have, by various elaborate investigations, proved that fatal septic poisoning can be produced in animals by the products of organic decomposition, without the presence of living organisms. Zweifel's experiments seem to have shown that normal blood, when deprived of oxygen, in the absence of micro-organisms, may acquire septic properties.

As stated by Belfield, many experiments by Schmidt, Edelberg, Köhler, Nencki, and others, have shown that septicæmia may be induced by the injection into the blood of free fibrin ferment and other substances, in the absence of minute organisms. To such an affection some authors now give the name sapræmia, to distinguish it from bacterial infective disorders.

Griffini ascertained that mixed saliva, filtered through porous plates, and thus containing no microbes, will still produce septicæmia in animals, when subcutaneously injected. Colin (1876) has denied the conclusiveness of the experiments of Chauveau, which have been held to prove the particulate nature of variolous and vaccine virus. Moreover, it is well known that eggs with shells unbroken are tainted when placed near others which are unsound.

7. While Klebs and Koch maintain the definite specificity of each minute microphytic organism, Nægeli and Billroth assert their mutual convertibility. Burdon Sanderson avers that "the influence of environment on organisms such as bacteria is so great that it seems as if it were paramount." Buchner, Grawitz, Greenfield, Pasteur, Wernich, Thorne, Willems, Law, Wood, and Formad report experiments making it appear that modification by culture is possible with bacilli and micrococci, converting an innocent into a malignant parasitic organism, or a death-producing microbe into one capable only of causing {146} a transitory and not dangerous local affection; which nevertheless secures to the animal thus treated immunity when subsequently exposed to the deadly infection. Most interesting have been the successes with such culture-inoculations obtained by Buchner, Greenfield, and Pasteur with anthrax in sheep; by Pasteur also in chicken cholera; and by Willems and Law with the lung-plague of cattle.

In none of these cases is there reported any morphological change whatever in the bacillus (Grawitz) or micrococcus (Wood and Formad); the change in the effects noted, and, in the case of the micrococci of malignant diphtheria, the acquired capacity of reproduction through several generations, are all.

8. The immunity against subsequent attacks on exposure (similar to the protection given by vaccination) continues to be without full explanation upon any theory. But it is especially difficult to reconcile it with the hypothesis of the infection being caused by, and dependent upon, the presence of peculiar microphytes. Why should not these, whether as parasites or as poisons, always produce the same effects?

9. The view entertained by Thorne, Wood, and Formad, that a common benignant affection, such as ordinary sore throat, may be converted into a violent infectious disease--e.g. malignant diphtheria--by modification of innocent micrococci into those with lethal characters, through local or bodily conditions, is sufficiently contravened by the great frequency of such conditions compared with the decided relative rarity of such malignant epidemics or endemics.

10. Throughout all the investigations which have been, and are likely to be, conducted, there remains the extreme difficulty, if not impossibility, of total separation between the microbes themselves and the matter of the vehicle in which they exist--the membrane, urine, blood, virus, artificial culture-material, or whatever it may be. All the effects ascribable to the disease germs may be, with no more difficulty, attributed to the toxic action {147} of a portion, however minute, of the soil in which they have lived, whose modifications must be concomitant with those which they undergo. It appears necessary, therefore, at the present time, to regard this whole question as still undecided, with a predominance of probability, however, in favor of the view that these minute organisms, or some of them, have a direct and important relation of some kind to the causation of specific endemic, epidemic, and contagious diseases. Altogether, the strongest arguments are on the side of the view that the micrococci, bacilli, etc. cause diseases, not as parasites, living upon their victims, but as poison-producers infecting them. The germ theory continues to be in the position of a probable hypothesis, not in that of an established doctrine of etiological science.

Practically, the result is nearly the same as if it were altogether settled, since it is admitted on all sides that the presence of microphytes (bacteria, micrococci, spirilla) coincides with those conditions under which originate several of the most malignant diseases. Measures which prevent the appearance or promote the destruction of these minute organisms are at least often, and to a great degree, preventive, if not curative, of such disorders; and the glory of Jenner's discovery, by which the ravages of small-pox have been made (potentially at least) controllable, seems not unlikely to be paralleled by the achievements of Pasteur and others in a similar preventive mastery over other maladies of men and animals. There is, therefore, no branch of inquiry in connection with medical science more worthy of being assiduously encouraged and extended. The present may almost be said to be, in the history of medicine, an era of myco-pathology.

For an exhaustive study of Etiology attention would now have to be given to the modifying influences affecting the occurrence and character of diseases in connection with age, sex, and temperament. But, as neither of these is ever, per se, causative of any malady, and they merely determine some modification of the action of morbid causes when these occur, want of space must be our justification for leaving them to be considered, in this work, in connection with the special causation of the different {148} diseases which will be hereafter described. A larger treatment of our present subject belongs rather to hygiene than to practical medicine.

MEDICAL DIAGNOSIS.

For the purposes of the medical practitioner all professional studies unite to the end of furnishing preparation for the diagnosis and treatment of diseases. At the bedside the cardinal questions are, How does the present condition of our patient differ from health? and, What ought we to do to bring about his recovery?