Wassilieff1 has shown that these micrococci only occur after the death of the tissue or tissues, that in these they may multiply so as to form extensive colonies, and that therefore the presence of these micrococci is only a secondary phenomenon.

FIG. 16.-CAPILLARY BLOOD-VESSELS OF NECROTIC MASSES FROM THE LIVER OF A MOUSE. THE CAPILLARIES ARE DISTENDED BY, AND FILLED WITH, ZOOGLEA OF MICROCOCCI.

In pneumonia accompanying certain infectious maladies, e.g. typhoid fever, tuberculosis, and even in severe catarrhal pneumonia, large masses of micrococci may occur in the air-cells.

FIG 17.-FROM A PREPARATION OF THE BLOOD OF A CHILD ILL WITH
INFANTILE DIARRHEA.

In those cases where lobules and whole lobes become transformed into solid structures-grey hepatisation-masses of micrococci may be found in the air-cells, and even growing into the blood-vessels in which stasis had set in. Such is the case

1 Centralblatt f. d. med. Wiss. No. 52, 1881.

in pleuro-pneumonia of cattle and in the pneumonia of swine fever. Pasteur has cultivated the micrococci in swine fever, and thought that he had reproduced the malady by inoculation. But this is not the case. The micrococci, although very abundantly present in the bowels and in the body,' have nothing to do with the malady. Pasteur's inoculations with the cultivated micrococci are quite fallacious; his positive results are no doubt accounted for by accidental air-infection, for this malady is highly infectious, and unless the most rigorous precautions are taken to obviate infection through the air, positive results may be obtained which in reality are due to accidental air-infection."

Micrococci occur always normally in large quantities in the fluids (saliva and mucus, &c.) of the nasal and oral cavities, pharynx, larynx, and trachea; they are derived no doubt from the atmosphere. On the papillæ filiformes of the tongue they form in some cases large masses.3 Pasteur has inoculated rabbits with the saliva of a child that suffered from hydrophobia, and having cultivated artificially the micrococci present in this saliva, thought to have discovered that a micrococcus (microbe spéciale) is the cause of hydrophobia. That saliva of the healthy dog and of man inoculated subcutaneously into rabbits sometimes produces death in these animals (Senator) had entirely escaped his notice, and Sternberg has proved this in an extensive series of experiments. His own saliva proved sometimes fatal to rabbits. They die of what is called septicemia, and Sternberg thinks it due to the micrococci; but this is not to be considered as proved.

All these micrococci stand therefore in no definite causal relation to the respective maladies, but are probably only of secondary importance.

The following micrococci are considered to stand in an intimate relation to specific diseases :

1. Micrococcus variola et vaccinia.-Chauveau7 was the first to prove experimentally that in vaccinia and in variola the active principle is a particulate non-diffusible substance.

I Reports of the Medical Officer, 1878, 1879.

2 Ibidem.

3 Butlin, "Fur of the Tongue," Proceedings of the Royal Society, 1880. 4 Comptes Rendus, xlii.

5 It is not quite clear whether this microbe spéciale is a dumb-bell micrococcus or a bacterium termo; it is quite possible that it is the latter, viz. a rod con stricted in the middle. If so, it would appear identical with the bacterium that produces Davaine's septicæmia in rabbits (see Chapter viii.).

6 Bulletin, April 30, 1881, National Board of Health, U.S.A. 7 Comptes Rendus, 1868.

Burdon Sanderson confirmed and extended this. Cohn 2 proved that the lymph of vaccinia and variola contains numerous micrococci. Weigert 3 showed for human small-pox, Klein for sheep-pox, that the lymphatics of the skin in the region of the pock are filled with micrococci, and Pohl-Pincus 5 traced their passage through the epidermis at the point of

ย

FIG. 18.-MICROCOCCUS IN THE FRESH LYMPH OF HUMAN SMALL-POX.

1. Singly.

2. In dumb-bells.

3. In short chains.

vaccination in the calf. The micrococci are very minute, according to Cohn's estimate 0.0005 mm. and less in diameter, single or in dumb-bells, or in shorter or longer chains, or in small groups. When cultivated on the warm stage, they form very long chains and colonies. In connexion with this it

FIG. 19.-LYMPHATIC VESSEL FROM THE SKIN OF A POCK IN SHEEP-POX The vessel is filled with micrococci.

must be mentioned, as stated on a former page, that similar micrococci occur also in the fluid contents of vesicles in the skin produced by various non-infective inflammations. To make it sure that the micrococci are the active principle, i.e. the causa morbi, it would be necessary to artificially cultivate them through several generations, and then, by re-inoculating 1 Reports on the Intimate Pathology of Contagion.

2 Virchow's Archiv, 1872, Keber, Hallier, Zürn. 3 Mediz. Centralbatt, 1871. 4 Phil. Transact. 1874. 5 Vaccination, Berlin, 1882.

them, to reproduce the disease. This essential link in the evidence is, however, still wanting.1

2. Micrococcus erysipelatosus.-The micrococcus is very minute, smaller than that of vaccinia. Lukomsky showed that, at the margin of an erysipelatous zone, that is the part where the disease is progressing and marked by the characteristic redness and swelling, the lymphatics of the skin are filled with zooglea of micrococci, and the injection of these vessels keeps pace with the progress of the erysipelatous process. Oth3 cultivated these micrococci artificially, and with such cultures produced by inoculation erysipelas in rabbits. Fehleisen placed this beyond any doubt, inasmuch as he produced successive cultures of these micrococci (derived from the lymphatics of erysipelatous human skin), and then by re-inoculation produced the disease not only in rabbits but also in man. Fehleisen found the micrococci only in the lymphatics of the affected parts, and these he cultivated artificially for fourteen generations-which it took two months to do-on peptonised meat-extract gelatine, and solid serum. The micrococci form a whitish film on the top of the nourishing material, and when inoculated into the skin (ear) of rabbits, a characteristic erysipelatous rash makes its appearance after from thirty-six to forty-eight hours, and spreads to the root of the ear, and further on to the head and neck. The animals do not, however, die from it. In the human subject he produced typical erysipelas after inoculation with the pure cultivated micrococcus in fifteen to sixty hours. These inoculations were justifiable because they were undertaken with a view to cure certain tumours. Thus one case of lupus, one case of cancer, one case of sarcoma, were considerably affected, and to the good of the patient.

Fehleisen also in several instances carried out successfully a second inoculation within a few months. The same observer also found that a 3 per cent. solution of carbolic acid and a 1 per cent. solution of corrosive sublimate destroys the vitality of this micrococcus.

3. Micrococcus diphtheriticus.-Buhl, Hüter, and Oertel had shown that in diphtheria the membranes include micrococci. Oertel 5 found this micrococcus in large numbers, not only in

I See the prize announcement of the Grocers' Company, London, 1883.
2 Virch. Archiv, vol. 60.
3 Archiv f. exp. Path. Bd. i 1874.

4 Die Aetiologie d. Erysipels, Berlin, 1883. 5" Experim. Unters. über Diphtherie," Deutsches Archiv f. klin. Med. Bd. viii. 1871.

the diphtheritic membranes of the organs of the throat and in their neighbourhood as well as in the surrounding lymphatics, but also in the blood of the general circulation, in the kidney, and in the muscles. The micrococci are about 0.00035-0001 mm, in diameter, are slightly oval, occur singly or in dumb

FIG. 20.-PORTION OF A DIPHTHERITIC MEMBRANE.
Numerous micrococci present.

bells or in short chains; they form also continuous masses of zooglea in the shape of spherical or cylindrical clumps, and as such they penetrate and destroy the surrounding connective and muscular tissues. In severe cases they are found blocking up the capillaries of the glomeruli and the uriniferous tubules of the kidney.

Besides micrococci there occur in the diphtheritic membranes also other (rod-shaped) bacteria, but these are evidently only accessory. Cultivations and inoculations with pure cultivations of this micrococcus are still wanting.

4. Micrococcus pneumonia.-In acute croupous pneumonia there occur in the affected lungs large numbers of micrococci ; Klebs, Eberth, Koch, Leyden, and others have seen them, but Friedländer 2 first pointed out their constant occurrence. According to this observer they are oval, of an oval nail-like shape, about 0.001 mm. long, and occur in the sputum singly, but especially as dumb-bells or diplococci, as chains, and as zooglœa. Ziehl found them in very large crowds in the sputum, giving to this in the early stages the peculiar characteristic brownish "prune-juice" tint. But this statement cannot be correct, since this tint may be very pronounced although the sputum contains only a limited number of the micrococci. According to this observer they are very numerous only in the beginning of the illness; after the critical stage they decrease in numbers.

1 Compare also Klebs, Archiv f. exp. Path. iv.; Letzerich, Virchow's Archiv, vol. 68; Nassiloff, ib. vol. 50; Eberth, Zur Kenntniss d. bact. Mycosen, 1872; Wood and Formad, Rep. of Nat. B. of Health, U.S.A. 1882. 3 Centralb. f. med. Wiss. No 25, 18S3

2 Virchow's Archiv, vol. 87.

E