DIGESTIVE TRACT, ETC. 49 



Digestive Tract, etc. 



In the grown-up amphibians, all of which avoid 

 vegetable food in the wild state — at least very largely 

 — the digestive tract is as simple as that of the fishes, 

 more so than that of some fishes. In many, the 

 stomach tends to be a mere swelled place in the long 

 tube, and there are very few kinks or bends anywhere. 

 There are no salivary glands, as in reptiles, and the 

 other organs, as liver, kidneys, etc., occur, but their 

 uses are much simpler than in the higher creatures. 



The tadpoles, however, are so largely vegetable 

 feeders that the digestive tract is long and much 

 twisted, as it always is where tough matter is to be 

 digested. But while the gills are being lost, the 

 limbs growing, and the lungs forming, it shortens up 

 into a much simpler form and takes a sudden step 

 backward — an instance of another wonderful emer- 

 gency met almost in a moment. 



