11.   Larger animals require more food than smaller animals, but smaller animals have a higher metabolic rate.

12.   Many animals have a single lens used to focus light on to a plate able to convert it into nerve impulses.

13.   Many poisonous animals have distinctive coloring that is easily recognized.

14.   Now consider an ingenious experiment which almost forces us to suppose that an animal has a cognitive map.

15.   Some rooms were covered in snow and all the animals there had white fur.

16.   The animals have a Marked preference for woodland.

17.   The animals would have to be fed on grain, which human beings themselves prefer to eat.

18.   The freedom of much animal behaviour from physically specifiable constraints implies that many animals must have inner representations and symbolic language.

19.   This is especially troublesome in urban homes, where the animals have little access to wooden posts or trees.