The accompanying letter was written by Prof. Ernst von Brücke a few months before his death.1 He had been professor of physiology at Innsbruck before coming to Boston.
Boston, Dec. 22, 1940
My dear Dr. Aub:
Ninety-four years ago, in 1846, my grandfather studied the reflection of light from the background of the human eye. It was this work that stimulated Brücke's friend, von Helmholtz, to invent the ophthalmoscope. My grandfather was the first one on whom von Helmholtz tried his instrument and the first person in whom he saw the background of the living eye.
These facts came back to me when you inspected my own retina, and I thought you might be interested in an old (so far as I know unpublished) daguerreotype of von Helmholtz (about 1848) which he gave to my grandfather. I should be happy if you would do me the favor of accepting
AUB JC. AN EARLY PHOTOGRAPH OF VON HELMHOLTZ WITH EXPLANATORY LETTER. Arch Ophthalmol. 1949;41(5):570-571. doi:10.1001/archopht.1949.00900040586004