SECT. XXI. PHYSIOLOGY. 181 
SECTION XXI. 
Vesical Irritability. 
cccecxL ix. The bladder is a fibrous bag, destined 
to receive the urine from the ureters; its capacity 
is considerable, which renders a frequent discharge 
of the urinary secretion unnecessary. Although 
inconsiderate theorists have brought the doctrine 
of final causes into contempt, there is no valid 
objection to them, when their purposes are obvi- 
ous; how miserable would human existence be, 
if the urine dribbled incessantly from the urethra, 
as it is secreted! How carefully have our 
convenience and comfort been studied, in the 
structure and functions of all our organs. 
ecccL. The expansibility of the bladder is 
entirely passive; what Fordyce has said of the 
stomach, is strictly applicable to this organ ; it is 
always full, whether it contains an ounce or a 
pint. The fibres of the bladder yield readily to 
the mechanical distention of the urine, but when 
this distention goes beyond a certain length, it 
produces an uneasy sensation, and desire to make 
water. 3 
