Haldan Keffer Hartline

Hartline tied the nuptial knot with Elizabeth Kraus in 1936. She was the daughter of eminent chemist, C.A Kraus. Elizabeth worked as an instructor in Comparative Psychology at Bryn Mawr College. The couple was blessed with three sons, Daniel Keffer, Peter Haldan, and Frederick Flanders.

Hartline breathed his last on March 17, 1983 in Fallston Maryland, United States.

Haldan Keffer Hartline was born on December 22, 1903 in Bloomsburg, Pennsylvania to David S Hartline and Harriet Frankline Keffer Hartline. Both his parents were teacher by profession.

Hartline was, in his early days, greatly influenced by his father, who was a Professor of biology but with varied interests going as far as astronomy and geology. Through senior Hartline, he developed an interest for Natural Sciences, one that stayed with him for the better part of his life.

Young Hartline received his preliminary education at State Normal School, the same school where his parents taught. After completing his early education, he enrolled at the Lafayette College in Easton, Pennsylvania. In 1923, he graduated from the same with a Bachelor degree in Science.

Encouraged by his college teacher Beverly W. Kunkel, Hartline took up research after his graduation. He submitted his first scientific paper on visual responses of land isopods. After spending the summer at the Marine Biological Laboratory at Woods Hole, he entered John Hopkins University in the autumn of 1923.

At John Hopkins University, Hartline was encouraged to continue his vision research in the Department of Physiology under E. K. Marshall and C. D. Snyder. He began his study of the retina electrophysiology. He used Snyder’s Einthoven string galvanometer to study the retinal action potential using frogs, decerebrate cats and rabbits. Within a framework of time, he recorded electroretinograms from animals, and also noted recognizable retinal action potentials from human subjects.

After attending the University of Leipzig and Munich, Hartline returned to USA to take up the position in the Eldridge Reeves Johnson Foundation for Medical Physics, at the University of Pennsylvania, under the directorship of Detlev W. Bronk.

At the Johnson Foundation Hartline began his studies on the activity of the single optic nerve fibre in the eye of the horseshoe crab, Limulus, recording the responses of receptor units under various conditions of stimulation and adaptation.

During the mid-1930s, he undertook the single fibre analysis of the optic responses of the vertebrate retina, principally in the eye of the frog. Eventually, he became the first scientist to isolate and record the activity of a single optic nerve fibre. He later showed that different fibres in the optic nerves respond to light in different ways. Early in the decade of 1940, Hartline also worked on problems of night vision in human subjects.

For a year from 1940 to 1941, Hartline served as an Associate Professor of Physiology at Cornell Medical College in New York City. However, he returned to Johnson Foundation and stayed therein until 1949.

In 1949, he accepted a position of the Professor of Biophysics and Chairman of the Thomas C Jenkins Department of Biophysics at the John Hopkins University. While serving as Professor of Biophysics Hartline recorded from the receptor units in the Limulus eye. He took to the studying of the inhibitory interaction in the Limulus retina, begun briefly several years before.

Hartline spent the major part of his career investigating the electrical responses of the retinas of certain arthropods, vertebrates and molluscs. Furthermore, he focused his study on the eye of the horseshoe crab (Limulus polyphemus). Hartline obtained the first record of the electrical impulses sent by a single optic nerve fibre when the receptors connected to it are stimulated by light. He later showed that different fibres in the optic nerves respond to light in different ways.