THE EFFECTS OF CROSS & SELF-FERTILISATION IN THE VEGETABLE KINGDOM. BY CHARLES DARWIN, M.A., F.R.S., ETC. CONTENTS. CHAPTER I. INTRODUCTORY REMARKS. Various means which favour or determine the cross-fertilisation of plants.--Benefits derived from cross-fertilisation.--Self-fertilisation favourable to the propagation of the species.--Brief history of the subject.--Object of the experiments, and the manner in which they were tried.--Statistical value of the measurements.--The experiments carried on during several successive generations.--Nature of the relationship of the plants in the later generations.--Uniformity of the conditions to which the plants were subjected.--Some apparent and some real causes of error.--Amount of pollen employed.--Arrangement of the work.--Importance of the conclusions. CHAPTER II. CONVOLVULACEAE. Ipomoea purpurea, comparison of the height and fertility of the crossed and self-fertilised plants during ten successive generations.--Greater constitutional vigour of the crossed plants.--The effects on the offspring of crossing different flowers on the same plant, instead of crossing distinct individuals.--The effects of a cross with a fresh stock.--The descendants of the self-fertilised plant named Hero.--Summary on the growth, vigour, and fertility of the successive crossed and self-fertilised generations.--Small amount of pollen in the anthers of the self-fertilised plants of the later generations, and the sterility of their first-produced flowers.--Uniform colour of the flowers produced by the self-fertilised plants.--The advantage from a cross between two distinct plants depends on their differing in constitution. CHAPTER III. SCROPHULARIACEAE, GESNERIACEAE, LABIATAE, ETC. Mimulus luteus; height, vigour, and fertility of the crossed and self-fertilised plants of the first four generations.--Appearance of a new, tall, and highly self-fertile variety.--Offspring from a cross between self-fertilised plants.--Effects of a cross with a fresh stock.--Effects of crossing flowers on the same plant.--Summary on Mimulus luteus.--Digitalis purpurea, superiority of the crossed plants.--Effects of crossing flowers on the same plant.--Calceolaria.--Linaria vulgaris.--Verbascum thapsus.--Vandellia nummularifolia.--Cleistogene flowers.--Gesneria pendulina.--Salvia coccinea.--Origanum vulgare, great increase of the crossed plants by stolons.--Thunbergia alata. CHAPTER IV. CRUCIFERAE, PAPAVERACEAE, RESEDACEAE, ETC.