EXCRETION BY THE KIDNEY. 499 
pable of performing their functions, death is the result, being 
preceded by marked depression of the brain-centers: passing 
into coma. Exactly which of the retained products brings 
about these results is not known. They are likely due to sev- 
eral, and it impresses on the mind the importance of those 
processes by which the constantly accumulating waste is elimi- 
nated. Uric acid when not removed from the blood and tissues 
is supposed to be the exciting cause of gout. An excess in the 
form of urates retained or deposited in certain parts, especially 
the joints, is frequently at all events an accompaniment of this 
disease. 
THE EXPULSION OF URINE. 
We now present in concise form certain facts on which to 
base opinions as to the nature of the processes by which the 
bladder is emptied. 
It will be borne in mind that the secretion of urine is con- 
stant, though of course very variable; that the urine is con- 
veyed in minute quantities by rhythmically contractile tubes 
(ureters) which open into the bladder obliquely; and that the 
bladder itself is highly muscular, the cells being arranged both 
circularly and obliquely, with a special accumulation of the 
circular fibers around the neck of the organ to form the sphinc- 
ter vesice. 
1. It is found that the pressure which the sphincter of the 
bladder can withstand in the dead is much less (about one 
third) than in the living subject. 2. We are conscious of being 
able to empty the bladder, whether it contains much or little 
fluid. 3, We are equally conscious of an urgency to evacuation 
of the vesical contents, according to the fullness of the organ, 
the quality of the urine, and a variety of other conditions. 
4. Emotions may either retard or render micturition urgent. 
5. In a dog, in which the cord has been divided in the dorsal 
region some months previously, micturition may be induced 
reflexly, as by sponging the anus. 6. In the paralyzed there 
may be retention or dribbling of urine. 7. In cases of urethral 
obstruction from a calculus, stricture, etc., there may be excess- 
ive activity of the muscular tissue of the bladder-walls. 8. 
Evacuation of the bladder may occur in the absence of con- 
sciousness (sleep). 
The most obvious conclusions from these facts are that—1. 
The urine finds its way to the bladder partly through muscular 
(peristaltic) contractions of the ureters, partly through gravity, 
