ABSTRACT
The research, of which in the following report I propose to give the first instalment, had for its object, first, to investigate whether and how far the Bacillus anthracis undergoes any change, morphologically and physiologically, when cultivated artificially ; and secondly, whether ordinary bacteria of putrefaction and septic fermentations can by artificial cultivations be so modified as when introduced into the body of an animal to be productive of disease, that is to say, whether it is possible for an innocuous saprophyte to assume the properties of an obnoxious pathogenic organism.
Reprinted from the ‘Reports of the Medical Officer of the Local Government Board for 1881.’
It is matter of regret that the exact methods of preparation used by M. Pasteur in his laboratory are not made public; so that the present research has had to be conducted in ignorance of his details. The fact of his success in producing what he calls a “vaccine” – a something which when inoculated into sheep produces some modified splenic fever that protects the sheep against the after-production of fatal splenic fever when the virulent material is inoculated into the sheep–may be taken as established.
According to this theory spores having been formed in the bacilli within the organs of a buried animal that has died of anthrax, such spores are taken up by earth-worms, carried up to the surface, and then deposited with their castings. Prom the surface of the soil they find easy access into the mouth or nostrils of animals grazing on that soil.
I shall show in a future report that tbe bacillus threads, as such, do not survive even the initial stages of decomposition of the buried body. And it cannot be supposed that earth-worras can feed on buried bodies in the few days that may elapse before decomposition has set in.
These appearances are much more striking in neutral cultivations than in those of acid or alkaline reaction. In the latter instances there is never the same copious growth as in the first.
These peculiarities of the early bacillus growth may or may not be connected with the ability of that growth, which is not possessed by later stages of the same growth, to kill mice that are inoculated with it. However that may be, these early peculiarities have no relation to spore formation. Spores have, indeed, nothing in common with these rounded ends and cubical cells, which stain in a way that spores do not stain, and have a quite different shape and refractive power.
What the meaning of the statement of Wernich’ s (‘Central f. med. Wiss.,’ No. 12,1882, p. 217) is, that rabbits, “although not absolutely refractory, nevertheless are very little susceptible” to anthrax, I cannot comprehend, since I have never found a rabbit escape death after inoculation with anthrax blood or artificially cultivated active Bacillus anthracis.
For convenience’s sake, I shall speak of the days of exposure of a cultivation to a constant temperature in the incubator, as being days of “incubation.”
In several instances of mice I have noticed what seems to denote a certain resistance offered to the anthrax virus on the part of white mice, viz. that some of my animals did not become affected by the virus the first or even the second time they were inoculated with it. Thus I noticed some that resisted the action of the cultivated Bacillus anthracis of a first cultivation; then they remained also unaffected by the introduction of typical anthrax bacillus threads of a second cultivation ; and on a third time being inoculated with blood bacillus remained nevertheless alive. They succumbed, however, on a fourth inoculation with bacillus spores of an artificial cultivation. Another mouse remained unaffected after the introduction of anthrax blood filled with bacilli, but succumbed to the influence of an artificial cultivation of anthrax bacilli filled with spores. The inoculation in these cases was carried out in the way described above, and I have no doubt that the material was properly introduced into the subcutaneous tissue of the tail. Not seeing any reason to accept in the first instances a refractivity of these particular animals to the anthrax virus,—for they succumbed to it ultimately, thus proving that they were susceptible to the virus,—it remains as the most probable explanation to assume that the virus, although locally introduced, was for some unknown reasons not carried into the general circulation. That in our instances it was the resistance offered by the tissue of the tail to the life of the Bacillus anthracis, which prevented the development of the disease, is not a probable reason, since there exists no real resistance to the anthrax bacillus, of either mice, rabbits, or guinea-pigs to prevent the fatal result generally produced after such incubations.
A similar negative result after first inoculation I have noticed also in a few of my guinea-pigs, where the fluid had been introduced into the subcutaneous tissue, and also in a sheep. But in both cases a second inoculation with the same virus produced positive results. The virus was introduced during the first inoculation in sufficient quantity very safely into the subcutaneous tissue.
As regards the slight effect (constitutional disturbance and rise of temperature) produced in cattle after inoculation with anthrax blood of rodents (Sanderson and Duguid),or with artificially cultivated Bacillusanthracis(P) of a rodent (Greenfield), as well as the non-fatal effect produced on sheep by Pasteur with his vaccine, we have to deal with peculiar conditions, not solely due to a diminution of virulence of the bacillus, but chiefly to some peculiarity (breed appears to be one of such peculiarities) of the animal inoculated. These cases are comparable in a certain sense to those mild cases of other infectious maladies, which not occurring more than once during the lifetime of an individual, would naturally confer immunity on this individual against a second attack. Thus, a person once having had a mild attack of scarlatina, measles, &c., very likely remains free from a second attack. In cases of scarlatina the differences in the severity of the attacks are due to differences of the source of the virus [i. e. differences of the nature of the virus], as well as to differences of the individuals attacked,—cases of varying severity being derived from the same source, i. e. the same virus. The same is also noticed in the cases of anthrax produced by the Bacillus anthracis ; the bacillus of some cultivations is altogether ineffectual on mice, deadly on guinea-pigs and rabbits, while it appears to produce, according to Pasteur, only a slight effect on sheep. Now, no one could say this difference is due entirely to a change of the bacillus, since it is equally due to the difference of the individual. Again, the non-fatal result with the blood bacillus of a guiuea-pig, dead of anthrax, produced in a cow contrasts strongly with the invariably fatal result produced by the same bacillus on mice, guinea-pigs, and rabbits.
It is very curious to find that Greenfield talks (‘Veterinarian,’ 1881) of a certain immunity against fatal anthrax conferred on cattle by his artificial cultivations, although these animals showed considerable illness after a farther inoculation with blood of man or guinea-pig dead of anthrax. He had already learned that cattle do not die after blood inoculation, even when not inoculated previously with any artificial cultivation. If he had inoculated his cattle with the blood of a guinea-pig or man (woolsorters’ disease), without previously inoculating them directly with artificial cultivations, the result would have been precisely the same This appears to me to furnish decisive evidence of Greenfield having had to deal, not with cultivations of Bacillus anthracis, but with some other harmless bacillus.
