324 FOUB-FOOTEB AMEUIGANS 



" Olive, quick ! the molasses is boiling over," cried 

 Dodo. And Mr. Blake had barely time to snatch off 

 the pot and prevent a great spill. 



" It's ready to pour out," said Olive, trying a little of 

 the mixture on a spoon; "then as soon as it is ropy, 

 we can begin to pull. Don't put it out on the snow, 

 Nat ; we want it to grow tough, not brittle, this time." 



* * * * Si 



" The next branch on the Mammal tree is a very deep 

 water one, the Whale branch, and the Dolphins and 

 Porpoises are sort of twigs on it," said Rap, studying 

 the picture. " The ladder says that Whale comes from 

 two words, meaning roller, and that they can't move on 

 land, and they live on animal food." 



" Yes," said the Doctor, " the Whales are all rollers 

 and the Porpoises too, though the Dolphins are quite 

 graceful and sportive, varying their rolling motions by 

 wonderful leaps, so that I do not wonder the mariners 

 chose them to be the mermaids' horses. 



" When this Whale tribe was developed. Nature set 

 out to build some Mammals like swimming oil-tanks, to 

 furnish light and heat to man until he should have 

 learned to bore into the earth and draw oil from wells. 

 As usual. Nature succeeded very well, and among these 

 Whales are numbered the largest living Mammals, some 

 species reaching eighty feet in length. All of this order 

 yield more or less oil, but the two most valuable species 

 are the great Sperm Whale, or Cachelot, and the Bow- 

 head. The Sperm Whale has, in a hollow in his head, 

 a lardy substance called spermaceti, from which candles 

 are made ; also yields a perfume called ambergris, and is 

 entirely covered, under the skin, with a layer of fat 



