ii. VINCENT'S WHITE MYCETOMA
Caused by Discomyces maduræ (Vincent, 1894). This kind of mycetoma is common and widely distributed. It has been observed in Algeria, in Abyssinia, in Somaliland, in the island of Cyprus, in India, in the Argentine Republic, and in Cuba.
It runs a slow course. Unlike D. bovis and other mycetoma-producing fungi, it does not destroy bone, and does not seem to act directly on the general health of the patient, though ultimately and indirectly it may bring about cachexia.
The grains formed by Discomyces maduræ vary in size from that of a pin's head to that of a pea. They are of a yellowish-white colour, present a mulberry-like surface, are soft and easily crushed. Their mode of growth is absolutely characteristic. The grain throws out from its periphery radiating filaments. Between these fungus threads are numerous lymphocytes (likewise arranged in radial series) embedded in an amorphous substance, probably arising from the destruction of lymphocytes, epithelial cells, and macrophages, on which the mycelium feeds. The crown of amorphous rays round the grain is typical. The grain is surrounded by numerous polynuclear leucocytes. Having attained from 1 to 1.5 mm. diameter, the grain projects small shoots which become detached from the parent grain, enlarge, and reproduce the characteristic radial structure. Other grains form also, and, after a time, the typical large mulberry granule is formed, the central grains degenerating. The grains are found in cavities surrounded by inflammatory connective tissue permeated by polynuclear cells and occasionally giant cells.
iii. NICOLLE'S WHITE MYCETOMA
Caused by Aspergillus nidulans (Eidam, 1883). So far only one case has been observed, in Tunis, but probably it occurs in many places, the parasite Aspergillus nidulans being widely distributed. The grains formed by this fungus may also attain the size of a pea, but they differ from those of Discomyces madurœ, inasmuch as they are more or less spherical and present a smooth surface.
In this form of mycetoma the bones are attacked and destroyed.
iv. BOUFFARD'S BLACK MYCETOMA
Caused by Aspergillus bouffardi (Brumpt, 1906). This form was discovered by Bouffard at Djibouti, Somaliland. Lewis seems to have met a similar case in India; a third case, probably also belonging to this species, was described by Bovo in Italy.
The grains are quite characteristic. They are black in colour and vary in size from a pin's head to that of No. 1 shot. They present a mulberry-like surface which is smooth and glossy. They are somewhat elastic, but break when pressed. Their structure is remarkable. It consists of a coiled-up mass. Maceration in water for about twenty-four hours causes the grain to unfold. Sections show that the grain is composed of a
