EXCRETORY AND REPRODUCTIVE SYSTEMS. 
165 
The substance of the kidney is composed of an outer 
cortical layer, about a half centimeter thick, and an inner 
medullary substance adja- 
cent to the pelvis, and pro- 
jecting into the latter in the 
form of a papilla. In the 
cortical substance are hun- 
dreds of Malpighian bodies, 
each composed of a ball of 
capillaries (Fig. 87) envel- 
oped by the invaginated 
enlarged extremity of a 
tubule which carries away 
the urine by a tortuous 
course to the papilla (Fig. 
88). In the Malpighian 
bodies the water and other 
mineral substances of the 
urine are extracted from 
the blood by means of the 
‘epithelial cells forming the 
inner wall of the capsule of 
Bowman. These urinary 
products pass through the 
proximal convoluted tubule 
and the loop of Henle to 
the distal convoluted tubule, 
where they are mingled 
with the urea extracted from 
the blood by the columnar 
epithelial cells of the tubule. 
SYSTEM 
MALE URINO-GENITAL 
WITH THE BLADDER PULLED TO 
ONE SIpe. 
a, Entrance of the urethra into the 
vestibule; ao, aorta; bl, bladder; 
cl, clitoris; en, cornu or horn of 
the uterus; ff, Fallopian tube, the 
left one is cut off; fm, fimbri- 
ated extremity of the Fallopian 
tube; kd, kidney; 1, ovarian liga- 
ment; ov, ovary; ra, renal ar- 
tery; rv, renal vein; rc, rectum; 
ur, ureter; ut, body of the 
uterus; uth, urethra; vc, vena 
cava; vg, vagina; vs, vestibule. 
From this point the excretions 
flow into the collecting tube which empties into the pelvis at 
the papilla. 
In a prepared microscopic section of the kid- 
ney, these Malpighian bodies and uriniferous tubules may be 
seen with a microscope magnifying about 200 diameters. 
