A Manual of Clinical Diagnosis - James Campbell Todd

FIG. 83.—Teichmann's hemin crystals (Jakob).

2. Teichmann's Test.—This depends upon the production of characteristic crystals of hemin. It is a sensitive test, and, when positive, is absolute proof of the presence of blood. A number of substances—lime, fine sand, iron rust—interfere with production of the crystals; hence negative results are not always conclusive. Dissolve the suspected stain in a few drops of normal salt solution upon a slide. If a liquid is to be tested, evaporate some of it upon a slide and dissolve the residue in a few drops of the salt solution. Let dry, apply a cover-glass, and run glacial acetic acid underneath it. Heat very gently until bubbles begin to form, replacing the acid as it evaporates. Allow to cool slowly. When cool, replace the acid with water, and examine for hemin crystals with two-thirds and one-sixth objectives. The crystals are dark-brown rhombic plates lying singly or in crosses, and are easily recognized (Fig. 83). Failure to obtain them may be due to too great heat or too rapid cooling. If not obtained at first, let the slide stand in a warm place, as upon a hot-water radiator, for an hour.

X. SPECIAL BLOOD PATHOLOGY

The more conspicuous characteristics of the blood in various diseases have been mentioned in previous sections. Although the great majority of blood changes are secondary, there are a few blood conditions in which the changes are so prominent, or the etiology so obscure, that they are commonly regarded as blood diseases. These will receive brief consideration here.

A. ANEMIA

This is a deficiency of hemoglobin, or red corpuscles, or both. It is either primary or secondary. The distinction is based chiefly upon etiology, although each type presents a more or less distinctive blood-picture. Secondary anemia is that which is symptomatic of some other pathologic condition. Primary anemia is that which progresses without apparent cause.

1. Secondary Anemia.—The more important conditions which produce secondary or symptomatic anemia are:

(a) Poor nutrition, which usually accompanies unsanitary conditions, poor and insufficient food, etc.

(b) Acute infectious diseases, especially rheumatism and typhoid fever. The anemia is more conspicuous during convalescence.