206 



TUB KEASON WHY. 



" God hatli made of one blood all nations of men for to dwell on all the face of 

 the earth." ACTS xvii. 



The pancreatic juice also enters through the same duct with the bile. But 

 its precise use is not understood. It is a fluid much like the salivary secretion 

 of the glands of the mouth. 



A B. Jugular veins which return 

 blood from the head to the heart. 



C. The superior venae cava, or 

 trunk vein, which pours the blood 

 returned from the upper part of th<? 

 system into the heart. There is a 

 similar large vessel which meets 

 this one and brings back blood from 

 the lower part of the body, and they 

 both pour the blood into the right 

 side of the heart. 



D E. The branches of the venous 

 system which bring back the blood 

 Irom the arms. 



F P. The great aorta, the blood 

 vessel which conveys arterial blood 

 from the heart, and gives off 

 branches that supply every part 

 of the body. 



G. Another large vein which re- 

 turns the blood from the muscles of 

 the chest, &c. 



H H. The thoracic duct,vfTnich re- 

 ceives the newly dissolved food from 

 the small absorbents, that collect 

 it from the intestines. It conveys 

 this nutrition (called chyle) upward 

 along the back, until it reaches 

 where the duct turns into the 

 junction of two veins, and pours 

 its contents into the veins bringing 

 blood back to the heart. The nu- 

 trition, therefore, is at this moment 



Fig. 50. GREAT VESSELS OP THE mixed with the venous blood, and 

 CIRCULATION, AND THE DUCT is sent to the lungs to be oxygen- 



WHICH CONVEYS NUTRITIVE . , 

 MATTER TO THE BLOOD. 



885. How is tlie nutrition taken away from the bilious 

 residue ? 



The muscular threads (or hands, as we figuratively call them) 

 continue to push forward the digested matter through a long tube, 



