206 



THE KEASOX WHY. 



' God hath made of one blood all nations of men for to dwell on all the face at 

 the earth." ACTS xvn. 



The pancreatic juice also enters through the same duet 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 vena cava, or 

 trunk vein, which pours the blood 

 returned from the upper part of the 

 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 

 from the arms. 



F F. 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, which 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. GBEAT VESSELS op THE mixed with the venous blood, and 



CIECULATIOK, AND THE DTTCT ig sent to t h e lungs to be OiygCU- 

 WHICH CONVEYS NUTEITIVE . , 

 MATIEE TO THE BLOOD. 



885. How is tlie nutrition taJcen away from the Ulious 

 residue ? 



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

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



