XVI CONTENTS 



Chapter VII. Illusions. — Eeality and appearance — 

 PreconceiTed 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- 

 shadovrs — Mirage — Need of explanation — Refraction of 

 light-rays — Dense air-strata — Illustration 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- 

 duced—Objects in water — Confused mirage — The swim- 

 ming wolf — Colors and shadows m mirage — Trembling 

 air — Beauty of mirage 109 



Chapter VIII. Cactus and Orease-Wbod. — 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 



