XIV ILLUSTRATIONS 



FACING PAGE 



Turtle embryo of about the same size as the human shown 



in Figure 32 92 



Photograph of the feet of daughter and mother who had 



six toes 106 



X-ray photographs of the feet of mother and daughter 



who have six toes 108 



Photograph of the hand of father, mother and daughter 



which illustrates heredity 110 



Variations in the size and shape of the heads of wheat 



in nature 114 



Five illustrations of timothy grown from the same amount 



of seed under the same conditions 118 



Photograph to show the eflFect of crossing one variety of 



wheat with another 118 



Ancient diseased fossil bone 130 



A similar bone tumor 130 



The fungus known as Amanita 138 



A potato showing the potato wart 142 



Photograph of a spruce tree 142 



The brain and interior part of the spinal cord of a 



salamander 152 



