Russian physiologist (1849–1936) best known for his investigation of conditioned reflex through the use of experiments involving salivating dogs. He was awarded the Nobel Prize in Medicine in 1904. Matte-finish 6.75 x 10 photo of Pavlov with his hat in one hand and a cane in the other, signed in ink “Prof. Dr. I. P. Pavlov.” The photo also bears a notation in another hand, “at Boston, August 1929,” at the lower right corner. Accompanied by a letter from the previous owner explaining the history and provenance of the item. In full: “According to Andrew J. Kozar, this signed photograph was obtained by Arthur H. Steinhaus at the 13th meeting of the International Congress for Physiology, Boston, August 1929. Steinhaus taught at George Williams College in Illinois and was a well-known researcher on the subject of sport physiology and exercise. Professor Andrew J. Kozar of the University of Tennessee obtained the photo from the son of Steinhaus in 1974 and it has been in his possession until the time of its transfer to me in May of 2008. [Signed] David E. Slough.” Ink just a shade light but clearly legible, and possible slight, neat trimming to edges, otherwise very fine, clean condition. Auction LOA John Reznikoff/PSA/DNA and R&R COA.