The author of this little brochure has been engaged for some time in the study of the development of reflexes. His original work has been mainly concerned with the earliest reflexes found in embryos obtained by cesarean section. He goes into detail concerning the changing types of reflexes, the conditional and the visceral reflexes, relationship between reflexes and instincts, and the dissolution of reflexes. The literature is thoroughly reviewed and a large bibliography is appended. The book is of great value to psychologists and neurologists as a summary of the most recent work in reflexes.