Purkinje, Johannes Evangelista, 1787-1869, Czech physiologist. While professor (1823-50) at the Univ. of Breslau he pioneered in establishing laboratory training in German universities. From 1850 he was professor at Charles Univ., Prague, and was active in the Czech nationalist movement. He improved microscope technique and made numerous contributions in the fields of histology and embryology. He discovered the apertures of the sweat glands and the large ramified nerve cells of the cerebellum now known by his name. In his research in ophthalmology he worked on the functions of the eye, studied subjective visual figures and recurrent images, and described important phenomena concerning the eye's sensitivity to color.