[133]

Tropæolum majus— plants bow will lean to Light in greenhouse slew a little from them — reversed Pot & placed before N.E. window — black on all other sides & top. — filament with triangle fixed to penultimate internode— traced on Horizontal glass — Height of Plants? —Length of internodes?

Distance from glass Left Hand [data not transcribed]

Apheliotropism Right Hand [data not transcribed]

(Used)

[133v]

19

Introduction

known to occur happen, and if when the net be damp is wet the pollen might may be injured. I used at first white cotton net' with very fine meshes, but afterwards a kind of net with meshes 1/10 of an inch in diameter, and this I found by experience effectually excluded all insects excepting Thrips, which no net will exclude. On the plants thus protected several flowers were marked with thread and were fertilised with pollen from the same flowers ; and an equal number borne by on the same plants were at the same time crossed with pollen from a distinct individual. The crossed flowers were never castrated; in order to make my the experiments as like as possible to what occurs under nature with plants fertilised by the aid of insects. Therefore some of the flowers which were crossed may have failed to be thus fertilised, and afterwards have been left fertilised. themselves But this and some other sources of error will presently be

147 156 146

[in margin:] specimen page

[Cross and self fertilisation, pp. 10-11: "My experiments were tried in the following manner. A single plant, if it produced a sufficiency of flowers, or two or three plants were placed under a net stretched on a frame, and large enough to cover the plant (together with the pot, when one was used) without touching it. This latter point is important, for if the flowers touch the net they may be cross-fertilised by bees, as I have known to happen; and when the net is wet the pollen may be injured. I used at first "white cotton net," with very fine meshes, but afterwards a kind of net with meshes one-tenth of an inch in diameter; and this I found by experience effectually excluded all insects excepting Thrips, which no net will exclude. On the plants thus protected several flowers were marked, and were fertilised with their own pollen; and an equal number on the same plants, marked in a different manner, were at the same time crossed with pollen from a distinct plant. The crossed flowers were never castrated, in order to make the experiments as like as possible to what occurs under nature with plants fertilised by the aid of insects. Therefore, some of the flowers which were crossed may have failed to be thus fertilised, and afterwards have been self-fertilised. But this and some other sources of error will presently be discussed."]