The Mentor: American Naturalists, Volume 7, Issue 9, Series No. 181, June 15, 1919, is a valuable collection of scholarly articles and studies devoted to prominent American naturalists of the time. The author of the book, Ernest Ingersoll, demonstrates his deep understanding of nature and its phenomena, revealing fascinating facts and conclusions to the reader. Each article in this edition is a separate masterpiece of scientific literature, helping to better understand and appreciate the greatness of American nature. "Teacher" will become an excellent source of knowledge for everyone who is interested in the amazing beauty of nature, as well as the history of the development of scientific research in the field of natural science.