FUNCTIONS OF THE STOMACH. 
389 
the rumen, and through the valvular fold, and into the reticu¬ 
lum, and had there become enveloped in mucus, and formed into 
a pellet) is pressed through the muscular pillars into the oeso¬ 
phagus, whilst, at the same time, another portion is forced 
through the valvular fold from the rumen, and is ready to enter 
the reticulum as soon as it has become relaxed. 
By the contractile action of the spiral muscle of the oeso¬ 
phagus this pellet is conveyed into the mouth, where it is 
remasticated and prepared for digestion. Here I cannot but 
allude to the beautiful designs of nature, as manifested in the 
structure and functions of the rumen. I should have mentioned 
before, that no change takes place in the food during its stay in 
the rumen except maceration, accomplished by the warmth and 
moisture in which it lay, and the alkaline principle that was 
developed ; and hence, that it was necessary that it should 
remain there some time in order to undergo that process. How 
has Nature provided for this? The food passes first into the left 
sac of the rumen, and is thence propelled into the right, which 
IS interiorly situated. How is it to be raised thence again? 
What power can throw the food from the lower into the upper 
stomach ? The right sac is always full; rumination goes no 
farther than emptying the left sac ; there is always plenty of 
food macerating there; and although no power would be able 
to throw the food from the lower into the upper stomach, yet 
when the upper one is filled as well as the lower, we can easily 
imagine that the muscles of the rumen are sufficiently strong 
to cause the food to revolve through the different compartments; 
and so that which had been long macerating will in its revo¬ 
lution pass into the upper stomach, and that which had been 
lately gathered, and lay at first in the upper sac, will descend 
into the lower one, and the process of maceration will be con¬ 
stantly going forward, and no food will re-ascend to the mouth 
for a second mastication which had not been duly prepared. 
This has been proved by experiment: a sheep was kept with¬ 
out food for several days, and when killed the right sac of the 
rumen was found full. 
Other experiments have proved that it is rarely that the food 
begins to be returned to be re-masticated in less than sixteen or 
eighteen hours, and that the return is not perfectly accomplished 
in less than double that time. It is, therefore, not the food that 
has been just swallowed that the cow ruminates, but that which 
has been macerating in the lower sac of the rumen for twenty- 
four hours upon the average. The singular division of the 
rumen into these two compartments renders it impossible for 
rumination to commence before both sacs arc foleiablv full, and 
