THE METABOLISM OF THE BODY. 439 
ings. Uric acid is found in the spleen, even of herbivorous 
animals, though not in their urine. 
G 
Blood-pressure. 
i 
Abscissa of Blood-pressure curve. 2 seconds intervals. 
TrlrTitrititrrty sires 
Fia. isaac aie of splenic variations in size, taken with the oncograph (after Roy). The 
increase in volume is indicated in upper curve by the ascent and the diminution by the 
descent. The tracing below is of the blood-pressure as taken in carotid artery of dog, 
The lower line indicates time markings. 
It is known that this constituent of the urine is increased in 
intermittent fever (ague), in which disease the spleen is often 
greatly enlarged. The vascular engorgement and the height- 
ened metabolism of the spleen seem to be associated; and the 
fact that the uric-acid diathesis is often intensified if not origi- 
nated by overfeeding, suggests a connection between the spleen 
and the digestive system at all events. Much as there is that 
remains obscure, we think it can not be doubted, on the evi- 
dence furnished, that the spleen must serve some very impor- 
tant purpose in the economy, apart from its relations to the 
blood, noticed in an earlier chapter. 
The dominion of the nervous system over the spleen is evi- 
dent from various facts. The spleen may be diminished in size 
either generally by the stimulation of the vagus or splanchnic 
nerves directly, or reflexly through stimulation of one of the 
afferent nerves; and, locally, by direct application of the elec- 
trodes to the surface of the organ. Stimulation of the medulla 
itself also leads to contraction of the organ. It would seem 
that not only the arteries but the organ as a whole is main- 
tained in a state of tonic contraction to a certain extent by the 
agency of the nervous system. Not only so, but, if we may 
judge from the analogy of other organs, we may believe that 
its metabolism is directly controlled by the nervous system, 
