64 PHYSIOLOGY AT THE FARM. 



mate principles into sugar. It has long been believed that, 

 besides affording a secretion of paramount importance in di- 

 gestion, the liver, in some other manner, contributed largely 

 to the maintenance of the animal economy in a healthy state. 

 These views have of late taken a more definite form. Thus it 

 is taught, that substances absorbed from the alimentary canal, 

 and brought with the blood of the portal vein into the liver, 

 there undergo important changes before being thrown into 

 the general course of the circulation. This is held to be par- 

 ticularly the case with incipient albumen or albuminose. The 

 proof of this, with respect to albuminose, is, that if it be 

 injected into the jugular vein, it speedily appears in the urine, 

 whereas, if injected into the portal vein, so as to be allowed to 

 traverse the liver, it is no longer ejected as a foreign substance, 

 but appears to become incorporated with the albuminous part 

 of the blood. 



With respect to the formation of sugar in the liver, a great 

 diversity of views prevails. In the mean time, however, the 

 liver may be considered as an organ destined to produce two 

 kinds of secretion namely, bile and sugar. The bile, being 

 chiefly excrementitious that is, fitted to separate something 

 from the blood, the retention of which would prove noxious 

 passes along the bile-ducts into the intestines, where it may be 

 subservient to some purpose connected with digestion, and 

 being afterwards in part absorbed, is finally eliminated during 

 the production of animal heat. The sugar being soluble may 

 be supposed to be taken up by the blood of the hepatic veins 

 and conveyed through the right side of the heart to the lungs, 

 where, being consumed in the respiratory process, it contributes 

 to the generation of animal heat. 



The quantity of bile secreted daily by the liver is very great, 

 amounting to several pounds weight ; and since but a small 

 proportion of decomposed bile is found in the excrement, it 



