CONTENTS. 



rECTUBE 



I. GUSTAV MAGNUS. IN MEMOEIAM .... 1 



II. ON THE ORIGIN AND SIGNIFICANCE OF GEOMETRICAL 



AXIOMS. ... . . . . . .27 



in. ON THE RELATION OF OPTICS TO PAINTING . . 7$ 

 I. Form. . . . . . . j . .78 



II. Shade . . - ".'.'-' 9* 



in. Colour . . . HO 



iv. Harmony of Colour . 124 



IV. ON THE ORIGIN OF THE PLANETARY SYSTEM . . 139 



Y. ON THOUGHT IN MEDICINE 199 



VL ON ACADEMIC FREEDOM IN GERMAN UNIVERSITIES . 237 



