FIG. 105.-FROM A SECTION THROUGH THE KIDNEY OF A RABBIT DEAD 36 HOURS AFTER THE INJECTION OF SPORES INTO THE JUGULAR VEIN.

In the upper part of the figure is a metastatic focus composed of Aspergillus spores and mycelium. In the lower half of the figure the urinary tubules and two Malpighian corpuscles are seen. (After Grawitz.)

properties, becoming capable of resisting the action of living tissues and of growing in them. This view has been proved to be incorrect by Gaffky,' Koch,2 and Leber. Those spores Mittheil. a. d. kais. Gesundheitsamte, 1880.

2 Berl. klin. Woch. 1881.

3 Ibid. 1882.

L

that do exert such pathogenic properties are not at all dependent on such acclimatisation, and are not ordinary moulds, but a distinct species of aspergillus (Lichtheim), which grows well at higher temperatures (38°-48° C.), and the spores of which under all conditions of growth are capable of producing in rabbits the mycosis in question.

(c) Penicillium.-In this fungus hyphæ, which are not septate, grow out from the mycelium; from the end of each of these arise like the fingers of the hand a number of short branched cylindrical cells, which give origin to chains of spherical spores.

The following two fungi belong to the order of fungi called Phycomycetes.

(d) Mucor is characterised by this, that from the mycelium hyphæ grow out which are not septate, and at the end of these a large spherical cell originates, sporangium, in which by endogenous formation a large number of spherical spores are developed; the wall of the sporangium giving way, the spores become free.

(e) Saprolegnia; colourless tubular threads, forming gelatinous masses on living and dead animal and vegetable matter in fresh water. The cylindrical or flask-shaped ends of the threads-zoosporangia-form in their interior numbers of spherical or oval spores-zoospores, possessed of locomotion (one flagellum at each pole) and which finally escape from the threads. These zoospores after some time become resting, surround themselves with a membrane, and finally germinate into a cylindrical mass which becomes transformed into the mycelium. Besides this asexual there is, however, a second or sexual mode of fructification, consisting in this: At the end of a mycelial thread a cell grows up into a spherical large ball, the oogonium. From the same thread, thin threads-antheridia -grow towards the oogonium, with the protoplasm of which they merge. This latter then differentiates into a number of spherical masses, the oospores, which become invested with a membrane. These become free and then germinate and grow into a mycelium. Saprolegnia grows on the skin of living fish, and causes here severe illness often terminating in death. Thus the salmon disease, as Professor Huxley has shown 1 is caused by this parasite. The zoospores of this salmon saprolegnia are, however, as Huxley has shown, as a rule non-motile. The hyphae of the fungus traverse the epidermis in the diseased patches of the salmon, and they bore through the superficial layer of the derma, a stem-part being situated in the epidermis, and a root-part in the derma; each of these Proceedings of the Royal Society, No. 219, 1882.

elongates and branches out. "The free ends of the stem-hyphæ rise above the surface of the epidermis and become converted into zoosporangia, more or fewer of the spores of which attach

FIG. 106.-SAPROLEGNIA OF SALMON DISEASE.

A sporangium filled with zoospores; in connexion with them several youngmycelial threads.

themselves to the surrounding epidermis and repeat the process of penetration." In saprolegnia associated with the salmondisease Professor Huxley observed only the asexual mode of fructification.

CHAPTER XVI.

ACTINOMYCES.

IN cattle there occurs a fatal disease, which is characterised by the formation of firm nodules of various sizes, due to a growth of small cells. In the centre of the nodules lie dense groups of peculiar club-shaped corpuscles-actinomyces· radiating from a firm homogeneous centre, and joined to this by longer or shorter, single or branched, filamentous stalks. Each of these actinomyces-corpuscles appears homogeneous, and of a bright slightly greenish lustre. These masses consist of what is called Actinomyces (Bollinger), and the disease is termed actinomycosis. In cattle the disease manifests itself by firm tumours in the jaw, in the alveoli of the teeth, and particularly by a great enlargement and induration of the tongue-"wooden tongue." On making sections through this latter organ there are found present in all parts microscopic tumours of small-cell growth. In the centre of each tumour is a clump of actinomyces. This clump is surrounded by a zone of largish cells, with one to four nuclei. The periphery of the tumour is made up of a fibrous capsule, with spindleshaped cells. Occasionally the tumours are to be seen also in the skin and in the lung; in the latter organ they appear as whitish nodules, easily mistaken for tubercles. Bollinger first described the disease in cattle.2 Israel 3 was the first to point out a disease in man characterised by metastatic abscesses (spreading it seems from a primary abscess of the jaw) in various internal organs, due to the presence of a fungus,

IPArg, Centralbl. f. med. Wiss. 14, 1882; Hink, ibid. 46, 1882.

2 Ibid. 27, 1877.

3 Virchow's Archiv, vols. lxxiv. and lxxviii.

which afterwards was identified as actinomyces, and Ponfick 1 has clearly established that in man it is not a rare disease.

FIG. 107.-FROM A SECTION THROUGH THE TONGUE OF A Cow DEAD OF ACTINOMYCOSIS.

A nodule is shown composed of round cells, in the centre is the clump of actinomyces surrounded by large transparent cells. Magnifying power 350.

FIG. 108.-A CLUMP OF ACTINOMYCES MORE HIGHLY MAGNIFIED, 700. According to careful observations, Johne 2 succeeded in transmitting the disease from cattle to cattle by inoculation, I Die Actinomykose des Menschen, Berlin, 1881. 2 Deutsche Zeitschr. f Thiermedicin, vii. 1881.