[Illustration: 1. Coccyx. 2. Semen. 3. Covering of the Thigh. 4. Great Sacro Sciatic Ligament. _a._ Bulb of the Urethra. _b._ Corpus Spongiosum. _c._ Crura of the Penis, being the conclusion of— _d._ Corpora Cavernosa Penis. _e._ Sphincter of the Anus. _f._ Levatores Ani, covered by a fascia or prolongation of the triangular ligament of the Urethra. _g._ Great Gluteal Muscles. _h, h._ Triangular Ligament of the Urethra. The artery of the bulb is seen on the left as it runs between the Crus Penis and bulb of the Urethra.] The Gluteal Muscles help the rotatory motion of the thigh, and give support generally to the buttocks. The Sacro-Sciatic Ligaments assist in the firm union of the bones of the pelvis. The Erector Muscles of the penis propel the urine and semen forward; and, by grasping the bulb of the urethra, push the blood toward the corpus cavernosum and the glans, and thus distend them. The Accelerator Urinæ Muscles, as their name implies, help to eject the urine and semen. The Triangular Ligament of the urethra assists the preceding purposes. _Testicles._—The testicles are two glandular oval bodies suspended in the scrotum. They furnish the male seed. They are supported by what is called the Spermatic Chord, which consists of the spermatic artery that supplies the testicle with arterial blood, whence the semen is concocted; the veins that return the superfluous blood, and the tube that conveys the semen to the urethra. The testicles are very liable to inflammation, and particularly to changes resulting from the wear and tear of human life—changes that not simply produce pain or inconvenience, but those whereby the power of the organs becomes partially if not wholly lost. A rather ample description of their complicated structure will show the necessity of attending to the earliest symptoms of disturbance. The testicles, in embryo, are lodged in the belly, but they gradually descend, and usually are found in the scrotum at birth. There are occasional exceptions, when one or even both testicles do not descend, but are retained in the groin. Mr. Hunter considered that their virility was thereby impaired, although such an opinion is negatived by numerous illustrations. The non-descent of the testicle, necessarily from its confined situation when in the groin, can not be so fully developed as where it is allowed to range in the scrotum. It is also exposed to accidents when retained, and cases have occurred where Hydrocele, a disease to be noticed hereafter, has ensued, producing much inconvenience, and occasionally the same has been mistaken for rupture. The testicles have several coats. The Scrotum should be considered as one, which is merely a continuation of the common integuments, exceedingly elastic, nearly destitute of fat, and possessing a peculiar contractile power of its own, whereby it can closely embrace the testicles, and at other times yield or become