TABLE OF CONTENTS. 



LETTER XXVI. Page 



Preliminary — The Magnolia Tribe — The Barberrj- Tribe . . 1 



LETTER XXVIL 



Pistil — The Gooseberry Tribe — The Vine Tribe . . .16 



LETTER XXVIIL 

 The Pittosporum Tribe — The Milkwort Tribe . . . s;6 



LETTER XXIX. 



The Jlignonette Tribe— Disk— The Caper Tribe . . .36 



LETTER XXX. 



The Cactus Tribe — The Gourd Tribe . . . . 44 



LETTER XXXI. 



The Begonia Tribe — The Fig-marigold Tribe — Hygrometrical Phenomena 



connected with the dispersion of .Seeds . . .56 



LETTER XXXIL 



The Lythrum Tribe— The Rock-rose Tribe — Mode in which the content- of 



the Pollen-grains are conveyed to the Ovule . • . »)7 



LETTER XXXIIL 

 The Tamarisk Tribe — The Sundew Tribe— Hairs of Plants . . 78 



LETTER XXXIV. 

 Venus' Fly-trap — Aanatomical .Structure of Leaves . . .87 



LETTER XXXV. 

 The Horse-chesnut Tribe — The Walnut Tribe . . .98 



LETTER XXXVI. 



The Houseleek Tribe — Purification of the Air by Plants — The Saxifrage Tribe 106 



LETTER XXXVIL 



The liurk-tlioru Tribe — Spines — The Spurge Tribe . .118 



