through the villi, the lacteals, the receptacle of the chyle, and the
thoracic duct (Fig. 77). Its passage through these places, like the
movements in all lymph vessels, is slow, and it is only gradually admitted
to the blood stream.

[Fig. 77]


Fig. 77—*Diagram of routes* from food canal to general circulation. See
text.


2. _Route of All the Nutrients except Fat._—Water and salts and the
digested proteids and carbohydrates, in passing into the capillaries, mix
there with the blood. But this blood, instead of flowing directly to the
heart, is passed through the portal vein to the liver, where it enters a
_second set of capillaries_ and is brought very near the liver cells. From
the liver it is passed through the hepatic veins into the inferior vena
cava, and by these it is emptied into the right auricle. This route then
includes the capillaries in the mucous membrane of the stomach and
intestines, the branches of the portal vein, the portal vein proper, the
liver, and the hepatic veins (Fig. 77). In passing through the liver, a
large portion of the food material is temporarily retained for a purpose
and in a manner to be described later (page 177).

*Absorption Changes.*—During digestion the insoluble foods are converted
into certain soluble materials, such as peptones, maltose, and
glycerine,—the conversion being necessary to their solution. A natural
supposition is that these materials enter and become a part of the blood,
but examination shows them to be absent from this liquid. (See Composition