CHAPTER XIY 



digestive tract, respiration, circulation, lungs, 

 heart, cold-blood, lymph-hearts, skeleton, 

 skull, muscles, nerves, brain, wisdom, skin, and 

 scales in reptiles 



The Digestive Tract 



In connection with long life there is nothing like 

 good digestion. In the Keptiles the salivary glands 

 first make their appearance — another thing which 

 came in with them. Digestion therefore in them 

 begins in the mouth, and that of the serpents is not 

 excelled in all Nature so far as quickly dissolving 

 lar^e masses of flesh is concerned. Other creatures 

 can excel them in digesting peculiar substances. Out 

 of these salivary glands the poison-glands are made, 

 which also, as noted, aid in digestion. 



The digestive tract in all reptiles is rather sim- 

 ple — especially in serpents where it is very slightly 

 twisted. In tortoises, however, and some lizards — 

 and especially the vegetable-feeders — it is more com- 

 plex. The liver is, of course, always present. 



Respiration and Circulation 



It is by the blood, after receiving oxygen from 

 the lungs, that the elements of the food are car- 



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