other lymphatic glands, in petechiæ, in the arachnoid, in ulcers involving the intestinal mucosa, and in papules and ulcers of the skin. It occurs also in the blood, though generally in very small numbers, being found there both in polymorphonuclear and mono-nuclear leucocytes, very rarely in the red corpuscles.[1] In the blood it is in greatest abundance towards the termination of the case, especially during fever, and when intestinal symptoms are present (Donovan).
The Leishman or Leishman-Donovan body, as it is generally called, is a small ovoid or roundish organism measuring from 2 to 4 μ in diameter. Stained according to Leishman's method, it shows two lilac-coloured chromatin masses, one larger than the other, enclosed in a cytoplasm having a faint bluish tint about the periphery. The larger chromatin mass is the nucleus, which may be oval and centrally placed (resting stage), or elongated and at the periphery (pre-division stage). The smaller chromatin mass is the micronucleus or blepharoplast; it is usually in the shape of a short rod, and is placed perpendicularly, or at a tangent to the nucleus. It stains more deeply than the latter. The parasites multiply by simple fission, the division of the body being always preceded by the elongation and division of the nucleus and blepharoplast. The plane of division is always longitudinal. Some forms, having attained a larger size, suggest a process of multiple fission; these are almost circular, and present, as a rule, six chromatin masses, three large and three small, the former being placed round the periphery.
The parasites, as they occur in man, are probably almost invariably intracellular. They grow and multiply within the host cell, causing it to enlarge, and then, after disintegration of the nucleus, to disrupt. The parasites so set free either enter other endothelial cells or are taken up by the white blood-corpuscles, in which they are sometimes found in the
- ↑ When existing in the blood in small numbers their presence can, in the hands of experts, be demonstrated by the N.N.N. cultural method. Centrifugation of the blood is of little use.
