ead of the epididymis;
4'', globus minor, or the tail of the epididymis; 5, vas deferens, the duct
through which the seminal fluid reaches the ejaculatory ducts; 5', pelvic
dilation of the vas deferens; 6, vesicula seminalis. The vesiculae seminalis
are two oval pouches, which, in addition to their own secretions, receive
the semen conveyed by the seminal ducts and hold it in reserve until
copulation; 7, membranous or intrapelvic portion of the urethral canal
covered by Wilson's muscle; 8, part of the prostate gland, covered by
Wilson's muscle; 9, Cowper's gland. This gland, like the prostate gland,
secretes a fluid which is thrown into the urethal canal in abundance
immediately before ejaculation; by this means the expulsion of the semen is
facilitated; 10, ejaculator seminis, or accelerator urinae muscle; 11,
penis; 11', cut portion of same; 12, cut suspensory ligaments of penis; 13,
sheath, or prepuce laid open; 14, retractor muscles of sheath; 15,
cremaster muscle cut at superior extremity; 16, duplicature of peritoneum;
17, ureters carrying urine from the kidneys to the bladder.

PLATE X. Microscopic anatomy of the kidney.

Fig. 1. In this figure the minute apparatus for the secretion, collection,
and discharge of the urine into the pelvis of the kidney (see preceding
plate) is shown. The course is as follows: The urine is secreted from the
blood vessels in the little round bodies called glomeruli (12), and by the
minute cells in the curved tubes (11, 9, 10, 8), and passes through the
convoluted and straight tubes (7, 6) into the larger tube (1), and then out
into the pelvis, thence through the ureters into the bladder. The fluid and
salts dissolved in the urine are taken from the blood, and the minute blood
vessels are therefore very abundant in the kidneys, as is shown by the
branches and network on the left of the figure. The blood passes into the
kidney in the artery (13), which then divides into branches which pass into
the glomeruli (12) and also forms network around the secreting tubules (11,
9). The urine and salts pass from these vessels through the cells lining
the tubules into the latter, and are discharged as described above. The
blood is again collected in veins drawn black in the figure.

Fig. 2 illustrates the manner in which the blood is distributed in the
glomerulus (_f_), and also to the secreting tubules (_e_).

Fig. 3 shows the relation between the blood vessel in the glomerulus (_e_)
the tubu