Spectroscope designed to replace the eyepiece in a microscope. The instrument, which analyzes light decomposed by a prism train, was used for the spectroscopic analysis of microscopic specimens such as blood samples. The sample was placed in a phial. Its spectrum, produced by a small additional prism, was projected in the field of view and served as the reference spectrum. The box contains a label with the name of Hartnack. Belonged to the Gabinetto degli Invertebrati of the Istituto di Studi Superiori of Florence.