MARTIN, Henry Newell, biologist, born in Newry, Ireland, 1 July, 1848. He studied at University college, London, and received the degrees of B. S. in 1870, M. B. in 1871, and Dr. Sc. in 1872, at the University of London, and was appointed university scholar in zoology and physiology. From London he went to Christ college, Cambridge, where he took the B.A. degree in 1874. He became a fellow of his college, and also lecturer on natural history. When the Johns Hopkins university was established, in 1876, he was invited to become its professor of biology, and he has since held that chair, and also the post of director of the biological laboratory. His original researches included experiments on "The Normal Respiratory Movements of the Frog and the Influence upon Its Respiratory Centre of Stimulation of the Optic Lobes" (1878), in which he explains, after careful examination, the respiratory mechanism of the frog and demonstrates that a nerve-centre able to check expiration exist in its mid-brain" "On the Influence of Stimulation of the Mid-Brain upon the Respiratory Rhythm of the Mammal" (1878)" and "On the Respiratory Function of the Internal Intercostal Muscles" (1879), in which he proved experimentally that in the dog and cat the internal intercostal muscles are expiratory, and therefore presumably so in man, thus settling a long-disputed point. In a series of papers (1881-'3) he was the first to demonstrate that the heart of a warm-blooded animal can be kept alive and beating normally for hours after general death of the animal, and by researches made on it in that condition, when beyond all control from the central nervous system or products of glandular activity or tissue change, that alterations in arterial or venous pressure do not directly cause any change in the pulse-rate" and that slight changes of temperature in the blood supplied to it very greatly influence the rate of beat of the heart by acting directly on it, hence showing that the quick pulse in fever is not a nervous phenomenon. His "Observations in regard to the Supposed Suction-Pump Action of the Mammalian Heart" (1887) show that this generally accepted action does not exist. Much of his work has been in collaboration with his pupils. Professor Martin was appointed Croonian lecturer of the Royal society of London for the year 1883, and in 1881 the honorary degree of M. D. was conferred on him by the University of Georgia. He is a member of scientific societies in the United States, and a fellow of the Royal society of London, and has contributed largely to scientific journals. He is editor of the "Studies from the Biological Laboratory" of Johns Hopkins, and associate editor of "The Journal of Physiology." He was associated with Thomas H. Huxley in the preparation of his "Practical Biology" (London and New York, 1876), and is the author of "The Human Body" (New York, 1881); and, with William A. Moale, of a "Handbook of Vertebrate Dissection" (3 parts, 1881-'4).