Spirochæte pallida is an extremely slender, spiral, motile thread, with pointed ends. It varies considerably in length, the average being about 7 µ, or the diameter of a red blood-corpuscle; and it exhibits three to twelve, sometimes more, spiral curves, which are sharp and regular and resemble the curves of a corkscrew (Fig. 129). It is so delicate that it is difficult to see even in well-stained preparations; a high magnification and careful focusing are, therefore, required. Upon ulcerated surfaces it is often mingled with other spiral micro-organisms, which adds to the difficulty of its detection. The most notable of these is Spirochæte refringens, which is distinguished by being coarser and having fewer curves of wider and less sharp contour (Fig. 130).
Spirochæte pallida is most easily demonstrated in chancres and mucous patches, although the skin lesions—papules, pustules, roseolous areas—often contain large numbers. Tissue-juice from the deeper portions of the lesions is the most favorable material for examination, because the organisms are commonly more abundant than upon ulcerated surfaces and are rarely accompanied by other micro-organisms. After cleansing the surface a superficial incision with a scalpel or sharp needle is made at the edge of a lesion, or the surface is gently scraped away with a curet, and a drop of blood and serum is expressed. The less blood the better, because the corpuscles may hide the spirochæte. Very thin cover-glass smears are then made.
Goldhorn's stain gives very good results. It can be purchased ready prepared from E. Leitz, New York. The unfixed smear is covered with the stain for four or five seconds. The excess of stain is poured off, and the preparation introduced slowly, with the film side down, into distilled water. It is held in this position for four or five seconds, and is then washed by shaking about in the water. By this method the Spirochæte pallida appears of a violet color, which can be changed to bluish black by flooding with Gram's iodin solution for fifteen or twenty seconds. The preparation is then washed, dried, and mounted.
SEMEN
Absence of spermatozoa is a more common cause of sterility than is generally recognized. In some cases they are present, but lose their motility immediately after ejaculation.
Semen must be kept warm until examined. When it must be transported any considerable distance, the method suggested by Boston is convenient. The fresh semen is placed in a small bottle to the neck of which a string is attached. This is then suspended from a button on the trousers so that the bottle rests against the skin of the inguinal region. It may be carried in this way for hours. When ready to examine, place a small quantity upon a warmed slide and apply a cover. The spermatozoa are readily seen with a one-sixth objective ([Fig. 53]). Normally, they are abundant and in active motion.
Detection of semen in stains upon clothing, etc., is often important. The finding of spermatozoa, after soaking the stain for an hour in normal salt solution or dilute alcohol and teasing in the same fluid, is absolute proof that the stain in question is semen, although it is not possible to distinguish human semen from that of the lower animals in this way.
| FIG. 131.—Seminal crystals (medium size) (X750) from a stain on clothing. A single thread one-eighth inch long was used in the test, the stain being three years and four months old (Peterson and Haines). |
Florence's Reaction.—The suspected material is softened with water, placed upon a slide with a few drops of the reagent, and examined at once with a medium power of the microscope. If the material be semen, there will be found dark-brown crystals (Fig. 131) in the form of rhombic platelets resembling hemin crystals, or of needles often grouped in clusters. These crystals can also be obtained from crushed insects, watery extracts of various internal organs, and certain other substances, so that they are not absolute proof of the presence of semen. Negative results, upon the other hand, are conclusive, even when the semen is many years old.
The reagent consists of iodin, 2.54 gm.; potassium iodid, 1.65 gm.; and distilled water, 30 c.c.