CONTENTS 
ix 
PAGE 
Piura and Chira — Topography -and mineralogy — Indig- 
enous vegetation — To Mr. Bentham^ — -To Mr. Daniel 
Hanbury (after his return to England) . . .312 
CHAPTER XXIII 
LETTERS AND ARTICLES RELATING TO HIS AMAZONIAN TRAVELS 
Spruce to Hanbury — On the winter sun and leafless trees — 
Spruce's account of Santander — Santander's letter to 
Spruce — Spruce to Hanbury — -Santander to Spruce — 
Essay on the Characteristics of Amazonian Vegeta- 
tion — The relations of Plants and Animals — Some cases 
of insect migration — Migrations of birds and mammals — 
Concluding remarks . . . . -343 
CHAPTER XXIV 
ON ANT-AGENCY IN PLANT-STRUCTURE 
Introductory remarks — Letter from Darwin — Letter from the 
Secretary of the Linnean Society — The paper — Of Sac- 
bearing Leaves — Of Inflated Petioles — Of Inflated 
Branches — Of Elongated and Fistulose Stems and Branches 
— Other evidence, with some remarks by the Editor . 384 
CHAPTER XXV 
ON INDIGENOUS NARCOTICS AND STIMULANTS, WITH THEIR 
USES BY THE INDIANS 
Remarkable narcotics of the Amazon and Orinoco — The use 
and effects of caapi — Niopo snuff and the mode of using 
it — Medicine-men and their customs — On spirits or 
demons among the Indians — A strange occurrence and 
its explanation — Rarity of curative drugs among the Indi- 
genes — Nerve -stimulants used by the Indians — Use of 
guarana as a tonic — Guayusa, a tonic used in the Eastern 
Andes — Conclusion . . . . .413 
