Key points are not available for this paper at this time.
Book 1: History of Linguistic Science 1. Before 1800 2. Beginning of the nineteenth century 3. Middle of the nineteenth century 4. End of the nineteenth century Book 2: The Child 5. Sounds 6. Words 7. Grammar 8. Some fundamental problems 9. The influence of the child on linguistic development 10. The influence of the child (continued) Book 3: The Individual and the World 11. The foreigner 12. Pidgin and congeners 13. The woman 14. Causes of change 15. Causes of change (continued) Book 4: Development of Language 16. Etymology 17. Progress or decay? 18. Progress 19. Origin of grammatical elements 20. Sound symbolism 21. The origin of speech
Sturtevant et al. (Mon,) studied this question.