Illustrations ix 



FACING 

 PAGE 



MODERN DIRECT-READING SPECTROSCOPE ...... 49 



By A. Hilger, Ltd. 



CHARLES DARWIN . . . . . . . . .56 



Photo: Rischgitz Collection. 



LORD KELVIN 56 



Photo: Rischgitz Collection. 



A GIANT SPIRAL NEBULA ......... 57 



Photo: Lick Observatory. 



METEORITE WHICH FELL NEAR SCARBOROUGH AND is NOW TO BE SEEN IN 

 THE NATURAL HISTORY MUSEUM ....... 57 



Photo: Natural History Museum. 



A LIMESTONE CANYON ......... 60 



Reproduced from the Smithsonian Report, 1915. 



GEOLOGICAL TREE OF ANIMALS ........ 61 



DIAGRAM OF AMOEBA .......... 61 



A PIECE OF A REEF-BUILDING CORAL, BUILT UP BY A LARGE COLONY OF 

 SMALL SEA-ANEMONE-LIKE POLYPS, EACH OF WHICH FORMS FROM THE 

 SALTS OF THE SEA A SKELETON OR SHELL OF LIME .... 64 

 From the Smithsonian Report, 1917. 



A GROUP OF CHALK-FORMING ANIMALS, OR FORAMINIFERA, EACH ABOUT 

 THE SIZE OF A VERY SMALL PIN'S HEAD ...... 65 



Photo: J. J. Ward, F.E.S. 



A COMMON FORAMINIFER (POLYSTOMELLA) SHOWING THE SHELL IN THE 

 CENTRE AND THE OUTFLOWING NETWORK OF LIVING MATTER, ALONG 

 WHICH GRANULES ARE CONTINUALLY TRAVELLING, AND BY WHICH 

 FOOD PARTICLES ARE ENTANGLED AND DRAWN IN . . .65 



Reproduced by permission of the Natural History Museum (after Max 

 Schultze). 



A PLANT-LIKE ANIMAL, OR ZOOPHYTE, CALLED OBELIA ... 68 

 Photo: J. J. Ward, F.E.S. 



TRYPANOSOMA GAMBIENSE ......... 69 



Reproduced by permission of The Quart. Journ. Mic. Sci. 



VOLVOX 69 



PROTEROSPONGIA ........... 69 



GREEN HYDRA ........... 72 



Photo: J. J. Ward, F.E.S. 



DIAGRAM ILLUSTRATING THE BEGINNING OF INDIVIDUAL LIFE . . 72 



