98 
STOMACHIC ABSORPTION. 
muscular structure of vena cava posterior and sub- hepatic 
veins as the horse, only less visible in proportion to their 
size. And what is remarkable, is, that in race-horses, I have 
uniformly found this muscular tunic at its highest degree of 
development.’ 5 * 
Now, is the muscular structure of the posterior cava and 
hepatic veins, of which we have ourselves received [several 
proofs of the existence, realty calculated to produce the contrac- 
tion of these vessels during digestion, and thus to favour the 
reflux of blood in the cava, which thus will become the 
representative of the renal vena portae? When we come to 
reflect, as taught us by M. Bernard, that no animal, in the 
same degree as the horse, presents so marked a muscular 
structure in the cava and hepatic veins ; and that this structure 
is at its highest development in race-horses, animals of extreme 
regularity and tried respiration ; that such is not the case with 
the large ruminants, in whom the abdominal venous system is 
predominant; we shall be led to acknowledge in him (the 
horse) an active agent of compression of the liver, under the 
influence of certain conditions which may retard or even sus- 
pend the hepatic circulation. Among these conditions may 
be placed, in the first rank, the immoderate pressure the liver 
sustains through the rapid oscillations of the diaphragm, 
regulated by the brevity of the respiratory motions, as under 
rapid races ; and that this disposition of muscular structure 
appears to us another argument to explain the great facility 
with which, under the influence of violent exercise, san- 
guineous congestion takes place, pro tempore , in the liver and 
spleen. 
We would likewise set upon a level with this important 
discovery of M. Bernard the alleged direct communications 
between the vena portae and vena cava, including those of the 
sub-hepatic veins. On this subject he expresses himself as 
under : 
“Vascular communications, which might be called direct 
anastomosis , take place by means of branches running directly, 
with open mouths, to open into the large vascular trunks. 
As an example, I will take the vessels of the liver of the 
horse and sheep. In these animals this mode of anastomosis 
is very manifest between the vena cava and vena portae, and 
it has the effect of establishing direct communications between 
the venous system in general The consequence of 
these anatomical facts is, that the venous systems of the cava 
and portae directly communicate in such a manner that a part 
* Comptes-rendus de la Societe de Biologie, 1849. — Notice sur les Travaux 
d’Auatomie et de Physiologie de M. Claude Bernard. 
