216 
EN’LARGED SPLEEN OF A HORSE. 
to contain thirty ounces of ^vater.’’ And also, ^^that the 
portal vein had been tied, and the spleen of the animals, that 
previously weighed only two ounces, has been found to 
increase to twenty ounces/^ These facts will give us some 
idea of the capacity, through the extensibility of this organ, 
it is capable of attaining, even in its normal condition; and 
it further suggests the almost unlimited size that may 
take plaee by persistent pressure and traction upon the 
tissue of which the framewmrk of the organ is chiefly 
composed. It may be asked, how can this force be applied 
so as to produce the effect alluded to ? Obstruction in the 
portal veins or in the hepatic circulation would be nearly 
equivalent to a ligature passed round the vena porta; 
and a similar effect, but not quite so direct, would be 
produced by any impediment to the flow of the blood 
through the posterior vena cava between the liver and the 
heart. Disease of the heart or the lungs, whereby the flow 
of blood through these organs becomes impeded, would 
tend to retard its return from the spleen, which, from its ex¬ 
tensibility, would yield to the force imparted to the blood 
by the heart in its passage through the splenic artery. 
Hyperaemia of this organ may take place from other causes 
than those I have alluded to; at least, I venture to suggest 
that it can. Muscular fibre is known to exist in the trabeculae, 
at any rate, in the smaller ones of the spleen of most animals, 
also in the middle coat of the blood-vessels; and as this 
tissue is supplied with nerves whose force determines the con¬ 
tractile power of the muscular fibre, and as the influx of blood 
into the organ, as well as the power of expelling it into the 
vein which conducts it to the vena porta, is greatly modified 
by this tissue, we can predict what the result would be if this 
force be withdrawn, and which we can understand might be the 
case. Disease of the splenic plexus of nerves to an extent 
sufficient to spoil them as carriers of nervous force would 
destroy muscular contractility, the effect would be atrophy 
of this tissue, relaxation of the coats of the blood-vessels and 
of the trabeculae also, with dilatation of the former and 
elongation of the latter, and thus the admission of more 
blood into the organ, and a diminished capability of getting 
rid of it, would be the consequence. Such a relaxed con¬ 
dition of the tissues, and a want of contractility appeared to 
be a prominent feature in the case in question. The inter- 
trabecular spaces were veiy capacious, and filled with a large 
amount of reddish-brown spleen-pul]), diffused through which 
was a quantity of a semi-gelatinous fluid. 
