Entire spermatozoa consist of long slender filaments, having a length of 0.04041 to 0.04512 millimetre; the anterior extremity presents an oval enlargement, either round or pyriform, exhibiting a double outline, when magnified to 500 diameters. This enlarged end is termed the "head;" the entire remaining portion being regarded as the "tail." In case the spermatozoa are broken, they are severed either near the head or in the middle of the tail, and a mass of detached fragments will be observed in the microscopic examination. The spermatozoa are not the only corpuscules revealed by the microscope; other substances, entirely different in character, are often observed. Although the detection of these bodies is, in itself, of no value, it will be well to enumerate and characterize them; they are: _a._ Oily globules. _b._ Leucocytes, or spherical and finely granulous globules of mucus. _c._ Corpuscules, originating from the seminal vesicles, termed sympexions. These are rounded or ovoid, possess an irregular outline, and are usually mixed with the spermatozoa and globules of mucus. _d._ Crystals of phosphate of magnesia, varying greatly in size; the largest are from 0.mm. 001 to 0.mm. 002 in length. The crystals formed upon cooling the semen, present the form of an oblique prism, with a rhomboidal base. Occasionally they are elongated and flattened; they then assume the form of a rhomboid. _e._ Epithelial cells; originating from the mucous follicles of the urethra. _f._ Irregular grains of dust; soluble in acetic and hydrochloric acids, with gaseous evolution. _g._ Brownish-red grains of rust; only slightly soluble in acetic acid, but easily soluble in hydrochloric acid. _h._ Filaments of the strained fabric; detected by their texture, and general appearance. _i._ Grains of starch, in case the cloth has been stiffened. These are almost invariably swollen, and are frequently broken and deformed. If the examination is to be secretly executed, and the cloth cannot well be cut, it is rolled in a cone, in such a way that the external side contains the stained portion. The lower extremity of the cone (which should be free from stains) is dipped in a watch-glass containing water, so as to avoid directly wetting the stains. The cone soon becomes moistened by absorption, and the operation is then completed in the same manner as when the fabric has been cut; which is always preferable, when possible. The examination of spermatic stains consists, then, in moistening the stains with water, separating them as completely as possible from the stained cloth, and determining the presence of the spermatozoa by means of the microscope. All other tests are valueless; even their execution for confirmatory purposes is not advisable; inasmuch as they fail to possess a distinctive character, and the reagents employed in their production may destroy the fabric, and thus prevent the formation of the only conclusive reaction--the detection of the spermatozoa.