QUESTIONS 211 



rain was withheld in South America. Speak of the birds in snow- 

 covered Ohio one winter. Why did some live and others die ? What 

 happened in Plymouth, Pennsylvania, in 1885 ? Describe the result 

 of the yellow-fever tests in Cuba in 1900. What did Darwin say 

 is sure to follow because of the law of variation ? Which creatures 

 will survive ? Give the fourth law in the linked chain. Show how 

 this law works itself out. What about long legs ? strong claws ? 

 keen eyesight ? What about power to go without water and to 

 survive famine ? How do we know that those who are best fitted to 

 survive are not always the largest, tallest, strongest, etc. ? Give an 

 illustration from the huge animals of South America. What about 

 the English sparrow ? Which birds best survive a storm ? How can 

 you explain the ears of the mole ? Give the final, supreme law of 

 Darwin's chain. What did Darwin believe about the ancestors of all 

 the wild animals that live to-day ; that is, how did he think they were 

 selected ? Apply the five-linked chain to last-year's codfish. Men- 

 tion some of the points on which all scientists agree. Which of 

 Darwin's statements do scientists accept with one accord ? What 

 did Darwin show about creative power ? 



CHAPTER X 



Describe the gill-slits of a fish (see footnote). Why does a fish 

 swim with its mouth open ? If it should keep its mouth shut, what 

 would result ? How does a fish get its needed supply of oxygen ? 

 Why does a fish die when it is drawn from the water ? Why do we 

 die when we are held under water ? In which embryos did scientists 

 expect to find gill-slits ? In which embryo do they always find gill- 

 slits ? What is an embryo ? Mention the different kinds of creatures 

 that have gill-slits when they are in the embryo stage. When ani- 

 mals are to live out of water after birth, what additional apparatus 

 does the embryo have ? Mention the rudiments of different animals. 

 What is a rudiment? How did Darwin explain a rudiment? De- 

 scribe the sacculina. How long does a sacculina live ? Give Darwin's 

 three statements about rudiments. When we find teeth in the 

 upper jaw of an embryo calf, what do we know about its ancestors ? 

 When we find rudimentary legs under the flesh of a full-grown 



