XVI CONTENTS 



CHAPTER VII. Illusions. Reality and appearance 

 Preconceived impressions Deception by sunlight Dis- 

 torted forms and colors Changed appearance of moun- 

 tains Changes in line and light False perspective 

 Abnormal foreshortening Contradictions and denials 

 Deceptive distances Dangers of the desert Immensity 

 of valley-plains Shadow illusions Color-patches on 

 mountains Illusions of lava-beds Appearance of cloud- 

 shadows Mirage Need of explanation Refraction of 

 light-rays Dense air-strataillustration of camera-lens 

 Bent light-rays Ships at sea and upside down 

 Wherein the illusion " Looming " of vessels, cities, and 

 islands Reversed image of mountains Horses and cattle 

 in mirage Illusion of rising buttes Other causes of 

 mirage Water-mirage The lake appearance How pro- 

 ducedObjects in water Confused mirage The swim- 

 ming wolf Colors and shadows in mirage Trembling 

 air Beauty of mirage 109 



CHAPTER VIII. Cactus and Grease- Wood. Views of 

 Nature Growth and decay Nature's plan The law of 

 change Nature foiling her own plans Attack and 

 drouth Preservation of species Means of preservation 

 Maintaining the status quo The plant-struggle for life 

 Fighting heat and drouth Prevention of evaporation 

 Absence of large leaves Exhaust of moisture Gums 

 and varnishes of bushes The ocatilla Tap roots Un- 

 derground structure Feeding the top growth Storage 

 reservoirs below ground Reservoirs above ground 

 Thickened barks Gathering moisture Attacks upon des- 

 ert plants Browsing animals Weapons of defence 

 The spine and thorn The crucifixion thorn The sting 

 of flowers Fierceness of the plant Odors and juices 

 Saps astringent and cathartic Expenditure of energy 

 The desert covering Use of desert plants Their beauty 



