quent fragmentation of the contents of the long threads, and later may be outside of the empty membranes (Fig. 20, c). These are not endospores! Older clubs become notched and cut, so that structures like an asparagus head may occur (Fig. 20, a). Often branched threads reach far beyond the zone with the clubs (Fig. 20, d). Sometimes clubs are entirely absent. Many actinomyces masses are dead when expelled in pus.

In cultures the branching mycelium is easily obtained (65, 1x); the clubs are found only in the deepest layers of the nutrient medium.

Staining Properties.-The threads, but not the clubs, are best stained by Gram's method; afterward the clubs may be stained red with saffranin and diffusely staining carmine. According to Berestnew (Z. H. XXIX, 94), young actinomyces clubs stain by Ziehl's method, sometimes also by Gram's method.

Relation to Oxygen.-Grows aerobically and anaerobically, but better aerobically (Boström). The growth is limited.

Chromogenesis.-The production of pigment is exceedingly variable; from white to various shades of yellow, orange, rusty, and brown appear to occur upon the various nutrient media; the darker tones at least predominate upon serum media, the brighter ones on gelatin.

Gelatin Plate.-(a) Natural size: After six days the

colonies have a very irregularrated above the sur

gray, shining,

face of the gelatin, sometimes growing deeply into it (65, IV).

(b) Magnified sixty times: Dark yellowish-gray, homogeneously shaded colonies, sometimes presenting more or less distinct concentric rings. The peripheral zone is dark and beset with fine, curly hair (65, vII).

Gelatin Stab.-Surface growth at first is whitish-yellow, flatly elevated, faintly shining, rather tough; later the growth sinks into the gelatin with the limited liquefaction, leaving an air-space above. In the stab at first there are small yellowish-white clumps, which later have bristly outgrowths (65, III).

Agar Plate.-Macroscopically and microscopically

Fig. 20-Formation of clubs in Actinomyces bovis. Harz (after Boström). (a, b, and c are highly magnified-about 1000 to 2000 times; d, e, and f, slightly magnified.)

scarcely distinguishable from those in gelatin plates, except that the colors are fainter.

Agar Streak.-At first delicate, like dewdrops; then there slowly forms (after six to ten days) a whitish to whitish-yellow growth with an abruptly scalloped border, faintly lustrous and fairly elevated. This gradually comes to resemble a growth of Mycobacterium lacticola with its elevated paddings and ridges. After a very long time (thirty days) the growth gradually becomes dry, sinks in, and the color changes from white to yellow or brown. The culture appears to grow deeper into the nutrient medium, and often becomes surrounded by a more delicate zone, but in our cultures, in distinction to Boström's, no air hyphæ and no downy appearance was formed. The water of condensation remained clear.

Serum Streak Culture (after Boström).-At first the colonies are like dewdrops, which first become a little broader and thicker; then, extending out from some places, a whitish, velvety, dry covering is obtained. While the surface of the colony which is turned toward the serum gradually becomes colored from yellowish-orange to brickred, as do the older, puffed portions of the growth,-a delicate border of transparent bristling hairs is formed about the growth, in which later there form anew little buttons and puffs, which are first whitish and then change to yellowish or reddish.

Bouillon Culture. The bouillon remains clear; at the bottom ball-like masses form, which are broken up with difficulty by shaking. Colonies upon the surface were never observed by us and rarely by Afanassiew. Microscopically the balls consist of threads with radially arranged fibers. Even in old bouillon cultures we could see no clubs.

Milk Culture. Unchanged after eight days.

Potato Culture. Slightly knobby, yellowish-white layer, closely attached to the potato, strictly limited to the streak. Often there occur distinct white, or yellow, and, according to Boström, also red spots (65, vm).

Special Nutrient Media.-According to Boström, the fungus also grows in non-albuminous nutrient media, and even in sterilized water, as it does in bouillon. In an

egg, Wolff and Israël obtained especially good dichotomous forms.

Conditions of "Spore-formation."-In many threads (not exclusively, but especially, with entrance of air) there are formed by continued transverse fission, short cocci-like and roundish oval bodies, which sometimes lie in close, but usually in broken rows within the empty and finally torn membrane (Boström, Kruse). Before the discharge of the "spores" the end of the thread is often somewhat swollen.

The "spores" stain like protoplasm, not

like the endospores of bacteria. We have seen nothing of these structures (Fig. 20, c) in either young or old cultures, although we took much pains to look for them. Typical conidia spores cut off in rows do not appear to be described.

Viability and Resisting Properties.-Very old cultures (nine months) are still alive.

Chemical Activities.-They have been but little studied. The odor is very faint, disagreeable but not moldy. From grape-sugar within eight days, neither gas nor acid is formed, and no H2S in peptone bouillon.

Distribution.—

(a) Outside the body: They have not been found, but must frequently occur upon the beards of grains and grasses, because infection most often depends upon the penetration of a fungus-carrying barley barb, which is often found in the actinomycotic swelling (Boström). (Compare Berestnew, p. 447.)

(b) In healthy body: Never found.

(c) In diseased human organism: It is the cause of actinomycosis. Principal ports of entrance: (1) Mucous membrane of mouth and throat; (2) respiratory tract; (3) intestine; (4) skin. Almost always beards and other parts of grain are the vehicle; more rarely, wood. From the primary areas the fungus is carried to all parts of the body by means of wandering cells and emboli. The disease in man produces soft granulation tissue, which is not encapsulated, and has a tendency to break down and to spread slowly but extensively to the surrounding tissue (chronic phlegmon). The formation of fistulæ favors the extension. More rarely there are distinct tumors, as in COWS. In the actinomycotic pus the actinomyces bodies are found. (See under Microscopic Findings.) There is scarcely a tissue or an organ of the body in which the actinomyces has not been demonstrated. Generalization of the actinomyces throughout the body is rare (see Messner, C. B. XIX, 487).

Recently acti

In 1892, 421 cases in man were known. nomycosis has also been observed in America.

(d) In animals: Especially in cows (rarely in swine, dogs, and horses). Formerly it was considered quite rare (1 in 10,000 to 1 in 3000), but it evidently is much more common, and simply overlooked. Sometimes it is epidemic. The localization is similar to that in man. Most often its seat is in the marrow of the upper and lower jaw; the marrow is traversed by soft granulation tissue and denser connective-tissue masses, the medullary cavity is enlarged, and new bone grows out from the periosteum (bony tumor). In other cases the soft parts of the face may be primarily attacked and the bones first involved from without. Also the pharynx and the wall of the stomach may be primarily attacked. The maxillary