gives rise to a typical fibrinous pneumonia. Thus the chief objection advanced against the etiological role of this microbe falls to the ground.

(319) Streptococcus Lanceolatus in Healthy Persons.

How is the fact to be explained that the streptococcus lanceolatus is found in the saliva of healthy persons? It is necessary to at once admit its frequent presence in normal saliva. Two cases in which Gamaléia found it most abundant were in the saliva of persons not suffering from pneumonia. Goldenberg has found the microbe in more than half the mouth secretions of healthy persons.

M. Pasteur has, a long time ago, shown that a disease of silkworms is caused by a common microbe which is found everywhere in the food of the worms, remaining inoffensive for those who have good digestion, and slaying those in feeble health or with weak digestive organs. M. Pasteur has also shown that the septic vibrio, a very virulent microbe, always exists in the intestines of the mammalia without troubling their health.

Gamaléia himself has found that the microbe of fowl cholera, so terrible for birds, is constantly found, although in small numbers, in their intestines, and that a poisoning by non-pathogenic bacteria suffices to open for them a portal into the blood.

It may, then, be believed that among healthy persons the streptococcus lanceolatus finds conditions opposed to its hurtful action. These conditions are only realised among animals little susceptible, as man, the sheep, and the dog; for the others, like rabbits and mice, succumb to the inhalation of the virus. Gamaléia has instituted direct experiments on this point. Whilst the virulent streptococcus introduced into the lung parenchyma of sheep always develops there a fatal fibrinous pneumonia, the same virus injected by the trachea does not kill. Thus, on more than twenty sheep, virulent pneumonic virus, injected into the trachea in quantities of 10 c.c., did not kill one. Hence it must be concluded that a lesion of the lung parenchyma, and an introduction. of the virus into this wounded parenchyma, are necessary conditions for the production of pneumonia in sheep. It was interesting to know the more intimate facts which pass after

intrabronchial injection. Gamaléia made the following experiment to elucidate this :

On May 11th, at nine a.m., three sheep were inoculated by intrabronchial injection with the virulent streptococcus. Body temperature before infection 40°-405 C., at seven p.m. 40.2 to 405. The first was killed in the evening. Autopsy, spleen soft and hyperamic; in both lungs and particularly at the apex of the right lung, regions very hyperæmic. The microscopical examination of this region revealed the presence of the streptococcus as well as an infiltration of mononuclear and polynuclear cells. These two varieties of "phagocytes contained masses of Pasteur's microbe. Free streptococci were rare. A mouse inoculated by the juice of the hyperemic lung succumbed the next day to septicemic pneumonia; some streptococci were found in the spleen, and in the disintegrated state (à l'état digéré), in the liver, and particularly in the kidneys.

On May 12th, at three p.m., the surviving sheep had a temperature of 39.6° and 39 2°. One was killed. The autopsy showed catarrh of the bronchial tubes; the walls of the tubes were hyperæmic and covered with rusty-coloured mucus (the injection was made from the blood of a lapin de passage). There were hyperæmic spots on the right lung. A microscopical examination showed the absence of the typical streptococcus in the lung. A squirrel inoculated by the pulmonary juice did not take pneumonia. The streptococcus, on the contrary, was abundant in the bronchial mucus, mixed, however, with other microbes, one of which was similar to that of Friedlander's microbe.

It is thus seen that the pneumonic virus, introduced into the trachea, does not determine the lesions of pneumonia in the healthy lung. It provokes a pulmonary hyperæmia and afflux of phagocytes which destroy the streptococcus. A few microbes pass into the blood, from whence they are eliminated in the ordinary way. But neither in the pulmonary alveoli nor in the capillaries are conditions found sufficient for the production of the pneumonic exudation. Microbes which are disintegrated or digested in the pulmonary alveoli and in the blood remain living in the bronchial mucus, and may, under favourable conditions, conduce to the development of pneumonia.

This is what happened indeed to the third sheep of the preceding

experiment. After remaining quite well during the experiment, it was inoculated in the eye by the virus of rabies, and succumbed on June 4th. The autopsy showed typical lesions of croupous pneumonia. The left lung was covered with a thick fibrinous layer of a gray colour, and was augmented in volume, and had all the other signs of pneumonia with fibrinous exudation, the pneumonic streptococcus was found in great number; the streptococcus was less numerous in the hepatised red and gray lung tissue, and was infrequent in the spleen and liver.

To better study the mechanism of immunity of healthy lungs, a microscopical analysis was made of the sputa of a subject who suffered from fibrinous pneumonia, and afterwards from chronic bronchitis; this subject expectorated masses of microbes, virulent to rabbits.

The sputum was tenacious, and adhered to the vessel; under the microscope it showed itself as a nearly pure culture of the specific streptococcus, with polynuclear globules, and endothelial cells, having a large nucleus and very granular. An attentive examination of these last cells, which have all the character of "macrophages," showed that they contained enormous numbers of the streptococcus of Pasteur in different phases of degradation. In the same cell with the typical form of the diplococcus may be found attenuated and angular forms which comparison alone connects with the specific microbe. One may in this way be convinced that the débris contained in the "macrophages" are the remnants of pneumonic microbes. The polynuclear leucocytes also contain the streptococcus but in much smaller quantity.

These phenomena give us the sought-for explanation of the immunity of the pulmonary tissue; the pathogenic microbes, even when they exist in very great quantity in the bronchial mucus, and arrive at the pulmonary alveoli, are stopped in their development by the macrophages who seize and devour them. In this strife the endothelial cells may themselves die and be rejected in the sputum. It is then clear that the production of pneumonia, or the maintenance of health, depends on the relative activity of the two orders of combatants. It may be also comprehended how the issue of the strife may be determined by slight predisposing causes, as cold, bronchitis, a fall, contusion of the chest, inhalation of irritating vapours and others.

In this way is explicable why the etiology of fibrinous pneumonia is composed of two factors-contagion, and the influence of the seasons with their action on the pulmonary cells.

To verify this Gamaléia has experimented on the pneumonic infection by first injecting substances capable of slaying the pulmonary" macrophages." Into the tracheas of six sheep was injected a solution of tartar emetic, four of them being inoculated, also by the trachea, with the pneumonic virus. One died the next morning from the inoculation, and the autopsy presented red hepatisation of the right lung in several places; a second had typical pneumonia, the third and fourth suffered from fever; "the control animals" remained healthy.

Hence we may conclude that influences injurious to the pulmonary cells predispose to the development of the streptococcus in the lung.

The conclusions that Gamaléia finally draws are:-That the streptococcus lanceolatus Pasteuri is always found in human fibrinous pneumonia. That this streptococcus produces in partially refractory animals fibrinous inflammation of the lungs. That its pathogenic influence is held in check in healthy men by the activity of the pulmonary phagocytes. He believes he has shown that human fibrous pneumonia is always caused by Pasteur's microbe.

(320) Bacteriology of the Middlesborough Pneumonia Cases.

Dr. Klein has made a careful research by the aid of modern methods on the micro-organisms in the cases of pneumonia in the outbreak recorded by Dr. Ballard (p. 416), and he draws the following conclusions:

(1) In the diseased lung of the Middlesborough pneumonia cases there were present in large numbers short bacilli, that are not Friedländer's bacillus nor the Diplococcus pneumonia of Frankel and Weichselbaum, but which upon cultivation and inoculation into rodents appear to be a definite species, distinctly different from either he therefore calls this bacillus the Bacillus Pneumonia. (2) Neither Friedländer's bacillus nor the Diplococcus pneumonia

:

1 Supplement to the Eighteenth Annual Report of the Local Government Board, 1888-89, 323.

of Frankel and Weichselbaum was obtainable from this human pneumonic lung by cultivation.

(3) The lung-juice of this pneumonia when inoculated into guinea-pigs, and especially when inoculated into mice, produced an acute disease, of which the chief and constant anatomical lesion was severe inflammation of the lungs. Mice were more susceptible than guinea-pigs.

(4) Artificial cultures of the Bacillus pneumonia from the human lung or from the blood of an experimental mouse proved very virulent to mice-less so to guinea-pigs. In mice these bacilli produced the same fatal disease as mentioned above, with conspicuous pneumonia.

(5) The blood and lung juice of mice and of guinea-pigs dead of the disease experimentally induced by the materials from the severally above recorded sources, produced on inoculation into other mice and guinea-pigs severe fatal pneumonia.

(6) In all experimental animals dead of the induced disease, the lung-juice (in mice also as a rule the heart's blood and the spleen), contained the bacillus pneumonia.

(7) By feeding mice with artificial cultures of the bacillus, the same pneumonia was produced, but not in so large a proportion of experimental animals as by inoculation.

(321) Preventive Measures.

Whether Gamaléia's views on pneumonia are correct or whether they will be modified by future research, there is good reason to class epidemic pneumonia as dependent upon sanitary state, and intimately connected with foul sewers, collections of filth and general air and soil pollution. It will be the duty of the health officer to inquire into cases of pneumonia as he would into any other septic disease, to enforce isolation where he can, and also to cause disinfection of the room, bedding and clothing after the termination of each case.