ON THE ACTION OF DIURETICS. 
639 
lating with the blood ; but this is neither a first nor an essential 
effect, nor yet one of great importance for the operation of the 
diuretic, unless perhaps it be in the case of so direct an irritant as 
cantharadine. 
Indeed, experience has shewn that in most cases medicaments 
of this class determine diuresis before they have had time to sensi- 
bly irritate the organs secretive of urine. On the contrary, such 
diuretics, independently of their operation on the kidneys, invaria- 
bly have a marked sedative effect on the centres of organic life ; 
whence results the retardation of the circulation and respiration, 
the slowness and weakness of the pulsations of the heart and 
arteries, the diminution of the animal heat, the lowering of the 
temperature of the skin, and such parts of the body as are distant 
from the centre of circulation, general debility, & c. Now, these 
depressive, counter-stimulant properties appear all to exert greater 
power over their diuretic agency than can be produced by means 
of direct irritation upon the secretory and excretory passages of 
the urine. There remains but this question to solve — Whether is 
the primitive or the secondary effect produced by such medicines 
diuresic or sedative ? The problem is not yet answered. Let us 
see what a highly competent individual, M. Trousseau, has to say 
on the subject. 
“ One very remarkable fact, to which sufficient attention has not 
been given, is, that all sedatives of the circulation are diuretics ; 
and, reciprocally, all diuretics exert a sedative effect on the circu- 
lation, commencing with cold, and proceeding to nitrate of potass, 
digitalis, squill, asparagus, ether, &c. Whence comes this com- 
monality of purpose, this intimate relationship between them in 
their action ? — for it is more than mere coincidence. There is no 
shutting one’s eyes to the connexion subsisting between more or 
less activity of the urinary secretion and the circulation of the 
blood. There is an evident physiological relation, of which the 
law has not been sought after. 
“ One fact strikes us at the outset, a fact opposed to precedent ; 
and that is, that all causes that increase the circulation, the calorifi- 
cation, the vegetative functions and action of the skin, diminish 
the secretion of urine. Such is the effect of general idiopathic 
fever, sweating, heating, pyretogenetic medicines. On the other 
hand, we see that every thing which has a contrary effect, every 
thing which suppresses the vegetative functions, diminishes the 
organic heat and cutaneous functions, lowering the action of the 
heart, &c., produces copious diuresis. 
“ So that one may estimate the sedative and anti- vital power of 
any therapeutic agent by its diuretic power, and vice versa. But 
is it the diuretic action which produces the sedative, or is the first 
