glands which form the digestive fluids are those which furnish
lubricating fluids, the lachrymal gland, and Harderian glands
in the orbit internally to the eye, and posterior and anterior to it
respectively, the sebaceous glands (oil glands) connected with the
hair, and the anal and perineal glands. The secretions of excretory
glands are removed from the body; chief among them are the sweat
glands and kidneys. The sweat glands are microscopic tubular
glands, terminating internally in a small coil (Figure VIII. s.g.) and
are scattered thickly over the body, the water of their secretion being
constantly removed by evaporation, and the small percentage of salt
and urea remaining to accumulate as dirt, and the chief reasonable
excuse for washing. The kidney structure is shown diagrammatically
in Figure 5, Sheet 7. A great number of branching and straight looped,
tubuli (little tubes) converge on an open space, the pelvis. Towards
the outer layers (cortex) of the kidney, these tubuli terminate in little
dilatations into which tangled knots of blood-vessels project: the
dilatations are called Bowman's capsules (B.c.), and each coil of
bloodvessel a glomerulus (gl.). In the capsules, water is drained from
the blood; in the tubuli, urea and other salts in the urine are secreted
from a branching network of vessels.