subcutaneously with emulsion of pyorrhoea pus in sterile broth, all but one guinea-pig and one rabbit died, in the majority of cases within forty-eight hours.

Some of the animals developed a local abscess at the seat of inoculation which when incised contained a thick viscid pus with an evil smell. Microscopically this pus contained the same morphological forms noted in the coverslip preparations from the original mouth lesion, but the organisms were not obtained in pure cultivation.

The broth cultures showed the same threads of lightly staining bacilli and gave off the same unpleasant smell as do tubes inoculated from the gum pockets.

The organisms found at the post-mortem examinations were by no means constant, the organism occurring in the largest number of cases being a bacillus, generally in jointed chains (streptobacilli). This organism was isolated in pure culture from three of the cases and re-inoculated into guinea-pigs, each time producing a fatal result; there was no abscess formation, but the organisms were recovered from the heart blood in pure culture.

From two of the cases Staphylococcus albus was obtained, and in one case B. mesentericus ruber. Several other organisms were also found in various cases, and there is therefore no sufficient data to draw any deductions from beyond the general facts that (a) the pus is decidedly pathogenic for animals, and that this pathogenicity is not apparently due to the common pus organisms; (b) that the organisms growing in broth cultures are able to elaborate a toxine (apparently by symbiotic activity) which when filtered produces death on inoculation into guinea-pigs. The condition would therefore appear to be primarily toxic, the suppuration with pus formation being a secondary matter.

The pneumococcus was not met with, nor has Bacillus coli appeared on the cultivations except in one case.

In two cases examined a yeast was obtained which caused death when inoculated intraperitoneally into guinea-pigs; the organisms were recovered from the peritoneal cavity in pure culture. Grasset1 obtained a pathogenic yeast from a mouth abscess, and the one I have isolated appears to be similar.

Troiser and Achlaime3 also describe a pathogenic yeast obtained

'Arch. de Med. Exp. et Anat. Path.

2 Fullerton. Journ. of Path. and Bact., 1900.

This

from the throat of a patient suffering from enteric fever. organism tended to form hyphæ in culture media, and is interesting in association with the general presence of yeast forms in pyorrhoea pus.

Hunter,' in a valuable communication, has called attention to the association of various general disturbances related to local conditions of oral sepsis, and points out conclusively the relation of "septic" gastritis, general septicemia, and the like, as well as a class of toxic conditions of an ill-defined nature, which owe their origin to uncleanly and suppurative conditions of the buccal cavity.

Hunter ascribes the symptoms to "the pus cocci so frequently present in the mouth," and quotes Miller, Galippe, Vignal and Arkövy. Miller, Netter, and myself, however, agree that the common pus organisms are by no means as frequent in the mouth as would seem probable-in fact only about 10 per cent. of cases examined give cultivations of these organisms. I have already shown, however, in the foregoing experiments that the pus of pyorrhoea, and the products of the activity of the organisms obtained, are extremely pathogenic for animals, thereby confirming Hunter's contentions; and there is no doubt whatever that the swallowing of these organisms and their products greatly influences the health of certain individuals. All persons with septic mouths, however, do not suffer from toxic poisoning, and several of the cases from which decidedly pathogenic results followed the injection of animals with pyorrhoea pus emulsion exhibited no impairment of health in any form, either gastric or general. It therefore becomes an interesting problem that toxic absorption does not always produce the gastric and other effects noted by Hunter.

We have already seen in the chapter on immunity that a large degree of tolerance may be produced in an animal by repeated injections of increasing doses of a given organism or its toxines. I have also referred to Ehrlich's theory of antitoxine formation, and we may I think apply the conception to an explanation of the tolerance to poisons produced in the mouth.

It is well known that individuals suffering from toxic mouth conditions may show no signs of poisoning for long periods, but that often such persons develop symptoms of toxæmia somewhat suddenly, and that once established the recovery is long and tedious.

1 The Practitioner, 1901.

Ritchie has recently shown that tetanus toxine if mixed with a proportion of acid does not give rise to tetanic symptoms when injected into a susceptible animal, but a degree of immunity is nevertheless produced.

It is quite possible therefore that some inactivation of the toxine produced occurs, and that a certain amount of immunity is produced thereby, but that under increased dose the immunity breaks down.

A NUMBER of bacteria occur with great regularity in all unclean mouths, and wherever any deposit of calculus exists. They exhibit the peculiarity that they will not grow upon ordinary culture media, at any rate when material containing them is inoculated directly from the mouth; they may appear in the abscesses and local inflammations produced in animals, by the inoculation of material taken from the gum margins. Miller was the first to attempt a classification of these mouth organisms, his tabulation being as follows:

(1) Leptothrix innominata.

(2) Leptothrix buccalis maxima.

(3) Bacillus buccalis maximus.
(4) Spirillum sputugenum.
(5) Spirochete dentium.

(6) Iodo coccus vaginatus.

Miller found that all these organisms refused to grow upon the ordinary culture media, and in no case was he able to obtain a pure cultivation; occasionally some of the bacteria grew a little, but they soon died out. This question of cultivation is one of the chief difficulties in isolating the above organisms, as not only do they require special media, but they are particularly susceptible to the presence of other bacteria; the mouth streptococcus, in particular, growing down almost all other forms.

It is probable that the morphological forms tabulated above will ultimately prove to be related to more than the six species they now represent, but until they have all been obtained in pure culture Miller's tabulation should stand. I have succeeded in cultivating two at least of the organisms in the above list, and it is to be hoped that the others may ultimately be obtained in pure culture. Two other organisms may be added to Miller's list, one the Leptothrix

racemosa of Vicentini, and the Streptothrix buccalis described by myself.

The Group Leptothrix.-A great deal has been written concerning "Leptothrix," and all sorts of curious things said of the doings of the mythical "Leptothrix of tooth decay." Any threadforming organism has been included under the term, so that not a little confusion exists in the nomenclature; more particularly has this arisen from the fact that no definite rule has been followed, and no proper definition of Leptothrix adhered to.

The term Leptothrix signifies a genus of bacteria belonging to the higher forms of Schizomycetes, and nearly related to the Crenothrix and Beggiatoia.

Zoph, in his classification of bacteria, describes the genus Leptothrix as "spherical, rod-shaped, and filamentous forms, the last showing a difference between the two extremities; spore formation not known, filaments straight or spiral." Migula has proposed as a family name for the various higher bacteria, Chlamydobacteriaceæ, and defines them as "filamentous bacteria composed of rod-shaped