PHYSIOLOGICAL CLASSES OF MEDICINES.

93

The intralobular veins open into the sublobular veins around which theFig. 29. lobules are arranged, and when a longi-

tudinal section is made, these lobulespresent a foliated appearance. The sub-lobular veins unite into larger branches,called hepatico-venous trunks.

Fig. 29.

a a. Sublobular hepatic veins.

6 6. Longitudinal section of lobules,c c. Basis of the lobules resting on the sublo-bular veins.

d. External or capsular surfaces of the lo-bules.

ee. Intralobular veins.

f. Projecting processes of the lobules.

g. Mouths of intralobular veins opening intothe sublobular vein.

Such, then, is the course taken bymedicinal agents in order to reach thehepatic vein, and by this the vena' cava.Now the lobular plexuses of the portalvein are accompanied by ducts to carryaway the bile as it is secreted.

'/ b

A longitudinal section of sublobular-hepatic veins , with lobules ar-ranged around them.

Fig. 30.

■srVssrV"•'oX,

Fig. 30.

a. Two lobules.

6 6 6. Interlobular ducts.cc c. The interlobular cellular tissue.d d. The external portions of the lobularbiliary plexuses injected.

e e. The intralobular branches of thehepatic vein.

ff. The uninjected central portions ofthe lobules.

But notwithstanding the many sub-stances which must ramify throughthe veins of the liver, only three orfour have, in modern times, beensupposed to exercise any specific influence in promoting the biliarysecretion: these are mercurials, aloes, and rhubarb. How far thesedeserve the appellation of cholagogues will be better examined when wenotice them individually.

8. Diuretics. —These are medicines which promote the secretion ofmine. They have derived their name from Ua, through; olpov, the urine;and peu>, I flow.

There are two principal modes of promoting the secretion of urine ;the one direct, the other indirect. The indirect method consists inaugmenting the quantity of fluids taken into the stomach, or in removingany cause which checks the secretion. The direct mode is to stimulatethe kidneys by means which specifically affect these organs. Thesemeans are the diuretics, properly so called. But almost all the sub-

Represents the intralobular ducts enteringthe lobules, and forming the lobular bi-liary plesmses.