DIGESTION. 



97 



which is the right side of the heart. The lacteals receive 

 their name from their milky-white appearance. After a 

 meal containing a por- 

 tion of fat, they are 

 then distended with 

 chyle, which they are 

 specially adapted to 

 receive: at other times 

 they are hardly dis- 

 cernible. The lacteals 

 all unite to form one 

 tube, the thoracic duct, 

 which passes upward 

 through the thorax, or 

 chest, and empties into 

 a large vein, situated 

 just beneath the left 

 collar-bone. 



39. The Absorb- 

 ents, The lacteals 

 belong to a class of 



vessels known as absorbents, or lymphatics, which ram- 

 ify in nearly all parts of the body, except the brain and 

 spinal cord. The fluid which circulates through the lym- 

 phatics of the limbs, and all the organs not concerned in 

 digestion, is called lympli. This fluid is clear and color- 

 less, like water, and thus differs from the milky chyle 

 which the lacteals carry after digestion : it consists chiefly 

 of the watery part of the blood, which was not required by 

 the tissues, and is returned to the blood by the absorbents 

 or lymphatics. 



40. Circumstances affecting Digestion. What 

 length of time is required for the digestion of food ? From 

 observations made, in the case of St. Martin, the Canadian 



FIG. 24. THE LACTEALS. 

 A, Small Intestine. B, Lacteals. 

 C, Thoracic Duct. D, Absorbents. 



E, Blood-vessel. 



39. The absorbents ? Lymph ? What further of tho lymph ? 



40. What can you state as to the time required for digestion ? 



