21. Ground plan of color discrimination apparatus

22. Cards for form discrimination

23. Labyrinth B

24. Labyrinth B on electric wires

25. Labyrinth A

26. Curves of habit formation for labyrinth B

27. Plan of labyrinth C, and path records

28. Labyrinth D

29. Curve of learning for white-black discrimination, twenty individuals

30. Curve of learning for white-black discrimination, thirty individuals

31. Curve of habit formation for labyrinth D

32. Curves of learning and re-learning

33. Plasticity curves