LIST OF ILLUSTRATIONS. 



FACING PAGE 



Plate 1. Weir Mitchell, 1829-1914 xvi 



Plate 2. John Lambert Cadwalader, 1837-1914 4 



Plate 3. Fig. 1. Front of New Animal House 132 



Fig. 2. Buildings at Station for Experimental Evolution : from left to right, 



Animal House, Pigeon Houses, Greenhouses, and Laboratory in the 



background. View looldng southeast 132 



Plate 4. The Observatory on Mount Wilson 241 



Plate 5. Headquarters and Laboratory of Department of Terrestrial Magnetism at 



Washington 298 



Plate 6. Fig. 1. View of Magnetic Station, Derna, Libia, Africa 312 



Fig. 2. Standardizing Magnetic Observatory of the Department of Terrestrial 



Magnetism at Washington 312 



Plate 7. The Magnetic Work of the Department of Terrestrial Magnetism, 1905-14. . 332 



VII 



