The play of young animals also in many cases gives important clues to lost ancestral habits, which are not now to be seen in adult life. The inherited tendency of animals to repeat, during their own development, the history of their race is very great; some striking cases of this will be considered in later chapters.
EXERCISES ON CHAPTER XIV.
1. Make a list of cases which you have observed of protective colouration in mammals, specifying (a) the colour of the animal, (b) the colour of its surroundings.
2. Describe any cases which you have observed of mammals having differently-coloured coats in summer and winter. Of what use is the change in colour?
3. Make a list of the mammals you know from observation to walk (a) flat-footed, (b) on their toes, (c) on the tips of their toes.
4. Make a list of the mammals which habitually hop, walk, fly, and swim respectively; and find out, by observation if possible, how the structure is adapted to the method of life.
5. Study the habits of the mole, and try to discover by what modifications it is enabled to burrow so rapidly.
6. What is the difference in the ways in which cows and horses get up and lie down?
7. For what purposes do the following mammals use their tails—cows, squirrels, rabbits? What mammals do you know which are without tails?
8. Observe and describe the differences—apart from speed—between walking, trotting, and galloping, in the case of the horse.