104 FOUR-FOOTED AMERICANS 



Men gave him, in addition to his English one. This 

 ladder is arranged so that when you liear a story of an 

 animal, you uau look at it and see in what family lie 

 helongs, in what guild he works, and his place in the 

 tree. If we ever make our stories into a book we 

 will put this ladder at the end to help little people who 

 might not be able to climb our tree without it." 



" Are those fourfoots all made into families and 

 guilds '! How is it done, by watching their claws and 

 mouths, what they eat, and the way they work, the 

 same as with the birds ? " 



" Partljr," said the Doctor, laughing, " only it is teeth 

 and feet with Mammals, instead of bills and claws. 



"The Wise ]Men, by measuring, comparing, and 

 studying the bones of these Mammals, have divided 

 them into groups or classes, keeping those the most 

 like together. Tiiis is called classification, and is very 

 important. If they had not done this, j-ou would never 

 guess, by looking at pictures or at stuffed animals in a 

 Museum, that a Whale is one of your blood brothers 

 and not a great fish ; or that tlie Bat, tliat you see 

 flitting about at twilight, is not a bird." 



" I'm sure it takes a lot of believing to know that a 

 Whale isn't a fish anyway," said Nat. " Do Mammals 

 ha\c tiiols to work with the same as birds liave chisel 

 and hooked liills and all that ? " 



" Yes, every Mammal has either a tool or weapon, 

 and sometimes the same thing answers for both, as you 

 will see." 



" You need not trouble yourself with learning your 

 ladder by heart all at once ; but when you have heard a 

 story about an animal, go to the ladder and it will help 



