[Francis Marion Hamlin was born in Owasco, N. Y., January ii, 1841. He attended the district school near his home, and soon mastered allthat was taught there, and was sent to the academy at Red Creek, N. Y. After completing the course he taught in the school. In September, 1863, he entered the Fort Edward Institute, and graduated with honors in July, 1865. He then began the study of medicine, and in September, i866, matriculated at the College of Physicians and Surgeons, New York City. He applied himself with such diligence that his health failed before the close of the year and he returned home. He was never robust, and all his life suffered after mental over-exertion. In 1867 Dr. Porter, of Skaneateles, directed his studies, and in December, x868, he graduated from the Albany Medical College. He did not confine himself to medical research only : he was an expert microscopist, naturalist and botanist. Soon after graduating he opened an office for general practice at Union Springs, N. Y. But wishing to make mental and nervous diseases a specialty, he accepted a place on the staff of the Government Hospital for the Insane of Washington, D. C., where he remained until the autumn of 1878. His health failed and he was obliged to rest for a long time. He spent three winters in Bermuda, where he became greatly interested in the study of conchology. He made an extensive collection of land and sea shells, and wrote a history of the fauna of these islands. During the last few years of his life Dr. Hamlin was in charge of the school for patients at the Willard State Hospital, Willard, N. Y. He died there March ii, ig#{231} o, of tuberculosis and chronic nephritis. The impressions he gained from his work are revealed in the following paper, which is a valuable contribution to an important subject in one of the by-ways of medicine and upon which very little has been definitely written. For the preservation of the manuscript and the opportunity for its posthumous publication we are indebted to the Albany Medical Annals and to the medical officers of the hospital.]